METHOD FOR CONTROLLING A HIGH-FREQUENCY FILTER IN A MOSFET DEVICE, AND A COMPUTER PROGRAM BASED ON SUCH A METHOD

Abstract

The invention relates to a method for controlling a high-frequency filter of at least one MOSFET device, having a source electrode and a drain electrode, and between these: - a DC connector module (DCL) supplying power; - at least one high-frequency filter; - gate control devices, the control method comprising the following steps: - a step of complete discharge (E0) followed by partial recharging (E1) of the DC connector module (DCL); - a step of short-circuiting said DC connector module (DCL) by connecting the high and low ends; - a step of determining (E3) the operation of said filter (RCS) based on a voltage measured across the terminals of the high and low ends. The invention also relates to a program based on such a method. Abstract figure: Fig. 2

Description

Title of the invention: METHOD FOR CONTROLLING A HIGH-FREQUENCY FILTER OF A MOSFET DEVICE, AND COMPUTER PROGRAM BASED ON SUCH A METHOD

[0001] The invention relates to the field of power modules for electrical devices, in particular for traction systems of electric vehicles. The invention relates more particularly to the control of high-frequency filters in these devices.

[0002] The power modules are highly integrated converters. In the context of the invention, this is a three-branch inverter, each branch having a high side and a low side with a number of MOSFET transistors in parallel.

[0003] For reasons of electromagnetic compatibility, one or more high-frequency RCS filters (or “RC snubber” in English) illustrated in the electronic system of [Fig.1], are provided between the drain on the high side H of the Mosfet device, and the source on the low side L of said Mosfet device.

[0004] A high-capacity DCL (or “DC link” in English) connector module is used to provide power.

[0005] In this electronic system, several gate control devices (or "gate drivers" in English) are used to control the gate of the Mosfet devices and open or close them.

[0006] The upper side H and the lower side L have pins producing a measurable signal.

[0007] Unfortunately, once the power module is built, it is difficult to determine whether the RCS high-frequency filter is functioning as intended. This is because if a conventional multimeter is connected to the pins of the high-H and low-L branches, it will measure not only the capacitance of the RCS high-frequency filter, but also a parasitic capacitance from the MOSFET device. Therefore, such a measurement does not allow for a determination of whether the RCS filter is working.

[0008] The capacitance of the RCS high-frequency filter can be measured on the power module before the Mosfet devices are placed on the printed circuit board (after the RCS filters are placed there), but this involves many constraints and manufacturing time for the power module.

[0009] An objective of the present invention is to remedy the defects of the prior art, and in particular to propose a solution enabling the detection of one or more defective high-frequency filters in a power module, and more particularly an inverter.

[0010] To achieve this objective, the invention proposes a method for high-frequency filter control of at least one insulated-gate field-effect transistor, said transistor having a source electrode and a drain electrode, said transistor comprising between the source electrode and the drain electrode: - a DC connector module providing power; - at least one high-frequency filter; - gate control devices enabling the opening and closing of the gate of said transistor, The control process includes the following steps: - a complete unloading step of the DC connector module; - a partial reloading step of the DC connector module; - a step of short-circuiting the DC connector module by connecting the upper part to the lower part; - a step of determining the operation of said high-frequency filter by means of a voltage measured across the terminals of the upper and lower parts.

[0011] Advantageously, short-circuiting the DC connector module of a tested branch closes the parasitic capacitance of the MOSFET device and discharges it rapidly. Furthermore, a high current appears, which facilitates the selective determination of the high-frequency filter capacitance.

[0012] Thanks to the invention, it is not necessary to implement a specific printed circuit board to determine whether said high-frequency filter is functional.

[0013] According to one embodiment, the step of determining the operation of said high-frequency filter is carried out by calculating the capacitance of said high-frequency filter on the basis of the formula p — —1—-where - F is a resonance frequency of the voltage measured across the terminals of the upper and lower parts; - L is the value of the resistance of said high-frequency filter; - C is the value of the capacitance of said high-frequency filter.

[0014] This allows the high-frequency filter capacity to be determined accurately.

[0015] According to one variant, the determination step determines a non-operation of said high-frequency filter when said measured voltage falls below a voltage threshold for a duration less than a duration threshold.

[0016] This makes it possible to detect if any high-frequency filter is working.

[0017] According to one embodiment, the control method is for a transistor whose gate control devices comprise: - a first set of grid control devices connected to the upper branch, enabling the implementation of a high-level control; and - a second set of grid control devices connected to the lower branch, enabling the implementation of a low control, the short-circuiting step of the DC connector module being implemented by simultaneously actuating the high control and the low control.

[0018] This simplifies the implementation of the short circuit of the DC connector module within the framework of the invention.

[0019] According to one variant, the step of partially recharging the DC connector module is carried out until the DC connector module reaches a voltage between 5 V and 50 V, preferably 20 V.

[0020] This allows us to have a sufficient load to determine the capacity of the high-frequency filter by limiting parasitic capacitances.

[0021] According to one variant, the control method is applied to several high-frequency filters in parallel, and the determined capacitance is divided by the number of high-frequency filters.

[0022] This makes it possible to determine the number of non-functional high-frequency filters.

[0023] According to one variant, the control method is applied to a power module comprising three branches, each equipped with said transistor, and the method is implemented successively on each of said branches.

[0024] This makes it possible to determine whether said high-frequency filter of each branch is functional.

[0025] The invention further relates to a computer program comprising program code instructions for executing the steps of the control method according to the invention, when said program is running on a computer.

[0026] The invention will be further detailed by the non-limiting description of variants, and based on the accompanying figures, in which: - [Fig. 1] schematically illustrates an electrical architecture of a MOSFET device suitable for implementing the invention; and - [Fig. 2] schematically illustrates the voltage V and current I across the components of the architecture of [Fig. 1], during implementation of the invention.

[0027] The invention relates to a method for high-frequency filter control of at least one insulated-gate field-effect transistor (or MOSFET device) in a power module such as an inverter of an electric vehicle traction machine.

[0028] The MOSFET device is equipped with a gate and comprises an upper portion H and a lower portion L. The upper portion H is connected to a source and the lower portion L is connected to a drain. These can be referred to as the source electrode H and the drain electrode L. In particular, the power module can have three branches, each having an upper portion H and a lower portion L, as well as a series of MOSFET devices in parallel.

[0029] The Mosfet device includes a high-frequency electronic filter system between the upper part H and the lower part L.

[0030] The high-frequency electronic filter system comprises: - a DCL connector module providing power; - at least one RCS high-frequency filter; - GD grid control devices allowing the grid of said Mosfet device to be controlled in opening and closing.

[0031] The GD gate control devices are arranged in two sets, one being connected to the upper branch H, enabling the implementation of a high CH control; the other being connected to the lower branch L, enabling the implementation of a low CB control. The two simultaneous controls allow the DC connector module DCL to be short-circuited.

[0032] The invention aims to determine whether said RCS high-frequency filter is functional.

[0033] According to the invention, the high-frequency filter control method comprises a The first step E0 is where the DC connector module DCL is discharged to 0 V. Then, power is allocated to the system, specifically on one of the three branches at a time, by charging the DC connector module DCL to a certain voltage, preferably a low value, for example 20V out of the possible 400 to 800 V.

[0034] In a second step El, the DC connector module is short-circuited by closing all the lower L and upper H sections of the MOSFET device on the tested branch. At this point, the parasitic capacitance of the MOSFET device is forced to zero voltage, it is rapidly discharged, and a large current appears.

[0035] In a third stage E3, only the capacitance of the high-frequency filter is still charged. A resonance effect is observed across the high-frequency filter voltage RCS between the high-H and low-B branches for several microseconds. This will depend solely on the capacitance of the high-frequency filter (but not on the parasitic capacitance of the MOSFET device since it is discharged), the parasitic inductances of the DC connector module DCL, and the DC bus bar.

[0036] The formula for the resonance frequency is as follows: F = -1—where - F is a resonance frequency of the voltage measured across the terminals of the upper part H and the lower part L; - L is the value of the resistance of said RCS high-frequency filters; - C is the value of the capacity of said RCS filters.

[0037] The inductance loop is known precisely from the sizing of the power module (by calculation or simulation). It is not expected to change significantly between inverters. Thus, it is possible to calculate precisely the value of the RCS high-frequency filter capacity based on measured frequency.

[0038] This capacitance value is equal to the capacitance of one filter multiplied by the number of functional RCS filters. Thus, it is possible to detect any faulty RCS filter.

[0039] To improve accuracy, it is preferable to test the three branches one after the other, applying the DC DCL connector module voltage only to one of the three branches at a time.

[0040] Figure 2 shows the evolution over time (in seconds) of the voltage V and current I across the various components during the charging of the DC connector module DCL, and then during and after the short circuit. The components are, from top to bottom: the DC connector module DCL, the high control system CH, the low control system CL, the high section H, and the low section L.

[0041] In use, if all the RCS high-frequency filters are functional, the resonance frequency is at its maximum; if some of said RCS filters are functional, the resonance frequency is lower than before; if none of said filters are functional, a very low resonance frequency is observed (or no frequency).

[0042] Thus, based on the oscillation frequency of the voltage across the upper H and lower L parts, it is possible to detect the number of functional RCS high-frequency filters.

Claims

Claims

1. Method for controlling a high-frequency filter of at least one insulated-gate field-effect transistor, said transistor having a source electrode (H) and a drain electrode (L), said transistor comprising between the source electrode (H) and the drain electrode (L): - a DC connector module (DCL) providing power; - at least one high-frequency filter (RCS); - gate control devices (GD) for controlling the gate of said transistor in opening and closing, the control method comprising the following steps: - a step of completely discharging (EO) the DC connector module (DCL); - a step of partially recharging (El) the DC connector module (DCL); - a step of short-circuiting (E2) the DC connector module (DCL) by connecting the source electrode (H) to the drain electrode (L);- a step of determining (E3) the operation of said high frequency filter (RCS) by means of a voltage measured at the terminals of the upper part (H) and the lower part (L).;

2. Control method according to claim 1, characterized in that the step of determining (E3) the operation of said high frequency filter (RCS), is carried out by calculating the capacitance of said high frequency filter (RCS) on the basis of the formula F - —!—rwhere - F is a resonance frequency of the voltage measured across the terminals of the upper part (H) and the lower part (L); - L is the value of the resistance of said high frequency filter; - C is the value of the capacitance of said high frequency filter (RCS).

3. Control method according to any one of claims 1 to 2, characterized in that the determination step (E3) determines a non-operation of said high frequency filter (RCS) when said measured voltage is lower than a voltage threshold for a duration lower than a duration threshold.

4. Control method according to any one of claims 1 to 3, for a transistor whose gate control devices (GD) comprise: - a first set of gate control devices (GD) connected to the high branch, making it possible to implement a high command (CH); and - a second set of gate control devices (GD) connected to the low branch, making it possible to implement a low command (CB), the short-circuiting step (E2) of the DC connector module (DCL) being implemented by simultaneously actuating the high command (CH) and the low command (CB).

5. Control method according to any one of claims 1 to 4, characterized in that the step of partial recharging (El) of the DC connector module (DCL) is carried out until the DC connector module (DCL) reaches a voltage between 5 V and 50 V, preferably 20 V.

6. Control method according to any one of claims 1 to 5, applied to several high frequency filters (RCS) in parallel, characterized in that the determined capacity is divided by the number of high frequency filters (RCS).

7. Control method according to any one of claims 1 to 6, applied to a power module comprising three branches each equipped with said transistor, characterized in that the method is implemented successively on each of said branches.

8. A computer program comprising program code instructions for carrying out the steps of the control method according to any one of claims 1 to 7, when said program is running on a computer.

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