Converter system and converter driving method

Abstract

To prevent a converter output voltage from becoming excessive when an open circuit fault occurs in a contactor.SOLUTION: A converter system 1 includes: a converter 5 electrically connected to a power source 2; a contactor 6 (6A, 6B) provided in a first power supply path 4 connecting the converter 5 and a load 3 and having an electromagnetic coil 14 for selectively conducting or interrupting the first power supply path 4; a contactor drive circuit 15 (15A, 15B) electrically connected to the electromagnetic coil 14 and driving the contactor 6 so as to close the contactor 6 by supplying power to the electromagnetic coil 14 when the converter 5 is operating and to open the contactor 6 by stopping the power supply to the electromagnetic coil 14 when the converter 5 is stopped; and a current sensor 19 (19A, 19B) that detects a contactor drive current flowing from the contactor drive circuit 15 to the electromagnetic coil 14. The converter 5 is configured to stop operation when the current sensor 19 stops detecting current during operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a converter system and a method for driving a converter in the converter system. [Background technology]

[0002] In recent years, efforts to realize a low-carbon or carbon-free society have become more active, and research and development into electrification technologies is being conducted in order to reduce CO2 emissions and improve energy efficiency in vehicles. In order to improve the driving performance of electric vehicles, it is important to provide a stable power supply from the power source to loads such as electric motors and inverters.

[0003] A contactor is provided in the power supply path to prevent excessive power from being supplied to the load if some abnormality occurs in the electric circuit, and a smoothing capacitor is provided in the power supply path to smooth the power supplied to the load.

[0004] For example, Patent Document 1 discloses a converter system in which a main contactor is provided in a power supply path from a battery to a DC / DC converter, which is a load, and a smoothing capacitor is connected in parallel to the load. This system includes a pre-charge contactor connected in parallel to the main contactor via a resistor, voltage sensors that detect the voltages of the battery and the capacitor, respectively, a current sensor that detects the current flowing from the battery to the load, and a control unit. The control unit controls pre-charging of the capacitor by opening and closing the pre-charge contactor, and also controls the opening and closing of the main contactor. The control unit determines that pre-charging is complete when the value detected by the current sensor is equal to or less than a threshold current. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7120072 Summary of the Invention [Problem to be solved by the invention]

[0006] In systems equipped with contactors, an open circuit failure may occur when, for some reason, the contactor driver circuit stops supplying power to the contactor, causing the contactor to open unintentionally. When a contactor open circuit failure occurs, the converter output voltage becomes excessive. For this reason, an overvoltage threshold is set for the converter output voltage detected by the voltage sensor to stop the converter.

[0007] However, even if the converter output is stopped after the converter output voltage exceeds the overvoltage threshold following an open circuit failure, there is a delay of a certain time between the time the output voltage exceeds the overvoltage threshold and the time the converter output is stopped. As a result, the converter output voltage exceeds the overvoltage threshold. In other words, in the event of an open circuit failure in the contactor, the converter continues to output voltage from the time the converter output voltage exceeds the overvoltage threshold until the converter shutdown operation is completed, resulting in an excessively high converter output voltage. Therefore, unless a capacitor with a sufficiently large capacitance is installed, the application of excessive voltage may damage electronic components, including the capacitor.

[0008] In view of the above background, an object of the present invention is to prevent the output voltage of a converter from becoming excessive when an open circuit fault occurs in a contactor. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, one aspect of the present invention is a converter system (1), comprising: a first power supply path (4) connecting a power source (2) and a load (5); a converter (3) provided in the first power supply path; a contactor (6) provided between the converter and the load in the first power supply path, the contactor having a normally open type movable contact (13) for selectively conducting / cutting off the first power supply path and an electromagnetic coil (14) for driving the movable contact; a contactor drive circuit (15) electrically connected to the electromagnetic coil for driving the contactor; The system includes a current sensor (19) that detects the contactor drive current flowing from the contactor drive circuit to the electromagnetic coil, and a control device (10) that controls the converter and controls the contactor drive circuit so as to supply power to the electromagnetic coil to close the contactor when the converter is operating and to stop the supply of power to the electromagnetic coil to open the contactor when the converter is stopped, and the control device is configured to stop the operation of the converter when the current sensor no longer detects a current while the converter is operating.

[0010] According to this aspect, if the current sensor stops detecting a current when a current is being output from the converter, the converter stops operating, thereby preventing the output voltage of the converter from becoming excessively high.

[0011] In the above configuration, it is preferable that the contactor (6) includes a first contactor (6A) provided on a positive power line of the first power supply path and a second contactor (6B) provided on a negative power line of the first power supply path, the contactor drive circuit (15) includes a first contactor drive circuit (15A) that drives the first contactor and a second contactor drive circuit (15B) that drives the second contactor, and the current sensor (19) includes a first current sensor (19A) that detects a contactor drive current flowing from the first contactor drive circuit to the electromagnetic coil of the first contactor, and a second current sensor (19B) that detects a contactor drive current flowing from the second contactor drive circuit to the electromagnetic coil of the second contactor.

[0012] According to this aspect, since the first and second contactors are provided, even if one of the contactors is stuck in the closed state, the power supply to the load can be stopped by opening the other contactor. Furthermore, even if an open fault occurs in either contactor, the converter stops operating when the current sensor on the side where the fault occurs no longer detects current, thereby preventing the output voltage of the converter from becoming excessive.

[0013] Another aspect of the present invention for solving the above-mentioned problems is a converter driving method in a converter system (1), the converter system including: a first power supply path (4) connecting a power source (2) and a load (3); a converter (5) provided in the first power supply path; a normally open movable contact (13) provided in the first power supply path (4) connecting the converter and the load, the normally open movable contact (13) being provided between the converter and the load in the first power supply path for selectively connecting and disconnecting the first power supply path; and an electromagnetic coil (14) for driving the movable contact. The converter includes a contactor (6), a contactor drive circuit (15) electrically connected to the electromagnetic coil and driving the contactor, and a current sensor (19) that detects a contactor drive current flowing from the contactor drive circuit to the electromagnetic coil. The contactor drive circuit controls the contactor drive circuit to supply power to the electromagnetic coil to close the contactor when the converter is operating, and to stop supplying power to the electromagnetic coil to open the contactor when the converter is stopped. If the current sensor no longer detects a current while the converter is operating, the converter stops operating.

[0014] According to this aspect, if the current sensor stops detecting a current when a current is being output from the converter, the converter stops operating, thereby preventing the output voltage of the converter from becoming excessively high. [Effects of the Invention]

[0015] According to the above aspect, it is possible to prevent the output voltage of the converter from becoming excessive when an open circuit failure occurs in the contactor. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a block diagram showing a functional configuration of a converter system according to an embodiment. [Figure 2] 1 is a time chart showing the operation of a converter system according to an embodiment of the present invention; [Figure 3] FIG. 1 is a block diagram showing a functional configuration of a converter system according to a comparative example. [Figure 4] 10 is a time chart showing the operation of a converter system according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments will be described as examples in which the present invention is applied to an automobile. The automobile may be any of a hybrid car, a fuel cell car, an electric car, etc.

[0018] Fig. 1 is a block diagram showing the functional configuration of a converter system 1 according to an embodiment. As shown in Fig. 1, the converter system 1 includes a power source 2, a load 3, and a first power supply path 4 (4A, 4B) connecting the power source 2 and the load 3. A converter 5 is provided on the first power supply path 4, i.e., between the power source 2 and the load 3 on the first power supply path 4, and a contactor 6 (6A, 6B) is provided on the first power supply path 4 between the converter 5 and the load 3. In other words, the converter system 1 can also be said to be a contactor system including the contactor 6.

[0019] The power supply 2 is configured by a power supply device mounted on the vehicle. The power supply device may be a battery fixed to the vehicle, a portable battery configured to be removable from the vehicle, a fuel cell, etc. The battery may be a lithium-ion battery, a nickel-metal hydride battery, etc. The power supply 2 is a DC power supply that outputs DC power and supplies the DC power to the converter 5.

[0020] The load 3 is, for example, a traction motor or inverter of an automobile. The traction motor may be an AC motor or a DC motor equipped with a permanent magnet. If the traction motor is an AC motor, the load 3 includes the traction motor and an inverter. The traction motor functions as a traction motor when the automobile is powered and as a generator when the automobile is braking.

[0021] The inverter may be configured as, for example, a three-phase bridge inverter. When the vehicle is powered, DC power is supplied to the inverter from the power source 2 via the converter 5. The inverter converts the DC power into three-phase AC power and supplies the AC power to the traction motor. When the traction motor is driven, the drive wheels are rotated and the vehicle moves.

[0022] The converter 5 is a DC / DC converter and includes an ECU 10 (Electronic Control Unit; an example of an electronic control device). In the converter 5, a capacitor for smoothing the output voltage is connected in parallel with the load 3. The ECU 10 controls the converter 5 to boost the DC power supplied from the power supply 2. The ECU 10 adjusts the output voltage to be applied to the load 3 to a desired value, thereby adjusting the drive current supplied to the load 3 via the first power supply path 4.

[0023] On the other hand, when braking while the vehicle is running, the inverter performs regenerative operation to cause the traction motor to function as a generator, converting AC power generated by the traction motor into DC power. The high-voltage DC power converted by the inverter is stepped down via converter 5 and supplied to power source 2. This charges power source 2. ECU 10 adjusts the charging voltage to be applied to power source 2 to a desired value, thereby adjusting the charging current supplied to power source 2.

[0024] The ECU 10 is a computer equipped with a processor (a processing unit such as a CPU or MPU) and a memory (a storage unit such as a ROM or RAM), and configured to execute various processes required for controlling the converter 5, etc. The ECU 10 is programmed so that the processor reads necessary data and software from the memory in accordance with execution commands from an external device such as an input device, and executes predetermined arithmetic processing in accordance with the software. The ECU 10 may be configured as a single piece of hardware, or may be configured as a unit consisting of multiple pieces of hardware.

[0025] The ECU 10 also includes a voltage detection circuit 11 that detects the voltage output from the converter 5 to the first power supply path 4. The first power supply path 4 is configured with a positive power line 4A and a negative power line 4B. The voltage detection circuit 11 is connected to the positive power line 4A and the negative power line 4B of the first power supply path 4.

[0026] The ECU 10 stores a preset overvoltage threshold. If the detection result of the voltage detection circuit 11 exceeds the overvoltage threshold while the converter 5 is operating, the ECU 10 determines that an abnormality has occurred in the voltage output from the converter 5 to the load 3, and stops the converter 5. However, there is a predetermined delay between the time when the output voltage of the converter 5 exceeds the overvoltage threshold and the time when the converter 5 actually stops.

[0027] The contactors 6 are electromagnetic contactors for selectively conducting or interrupting the first power supply path 4, and two contactors 6 (hereinafter referred to as a first contactor 6A and a second contactor 6B) are provided in this embodiment. The first contactor 6A is provided on the positive power line 4A of the first power supply path 4, and the second contactor 6B is provided on the negative power line 4B of the first power supply path 4. Each contactor 6 includes a movable contactor 13 (contact) that selectively switches between an open state and a closed state, and an electromagnetic coil 14 that drives the movable contactor 13. Each contactor 6 is a normally open electromagnetic contactor in which the movable contactor 13 is in an open state when the electromagnetic coil 14 is not energized, thereby interrupting the first power supply path 4, and the movable contactor 13 is in a closed state when the electromagnetic coil 14 is energized, thereby conducting the first power supply path 4.

[0028] If the contactor 6 is provided in the first power supply path 4, a failure may occur in which the contactor 6 is stuck in the closed state. In this embodiment, since the contactor 6 includes the first contactor 6A and the second contactor 6B, even if one of the contactors 6 is stuck in the closed state, it is possible to stop the power supply to the load 3 by opening the other contactor 6.

[0029] Each contactor 6 is controlled by an ECU 10 of the converter 5. The ECU 10 has a first contactor drive circuit 15A that controls the first contactor 6A and a second contactor drive circuit 15B that drives the second contactor 6B. The first contactor drive circuit 15A is electrically connected to the electromagnetic coil 14 of the first contactor 6A via a first contactor power supply path 17A. The second contactor drive circuit 15B is electrically connected to the electromagnetic coil 14 of the second contactor 6B via a second contactor power supply path 17B. Each contactor 6 drive circuit applies a voltage to the electromagnetic coil 14 of the corresponding contactor 6 and controls the contactor drive current flowing through the electromagnetic coil 14, thereby driving the moving contactor 13 to open and close.

[0030] The ECU 10 also includes a first current sensor 19A that detects the contactor drive current flowing through the first contactor drive circuit 15A and a second current sensor 19B that detects the contactor drive current flowing through the second contactor drive circuit 15B. The first contactor drive circuit 15A supplies the contactor drive current to the electromagnetic coil 14 and closes the first contactor 6A when the converter 5 is operating, and opens the first contactor 6A without supplying the contactor drive current to the electromagnetic coil 14 when the converter 5 is stopped. The second contactor drive circuit 15B supplies the contactor drive current to the electromagnetic coil 14 and closes the second contactor 6B when the converter 5 is operating, and opens the second contactor 6B without supplying the contactor drive current to the electromagnetic coil 14 when the converter 5 is stopped.

[0031] If the first current sensor 19A stops detecting the contactor drive current while the converter 5 is operating, the ECU 10 determines that an open circuit failure has occurred in the first contactor 6A due to an abnormality in the first contactor drive circuit 15A, and stops the operation of the converter 5. Also, if the second current sensor 19B stops detecting the contactor drive current while the converter 5 is operating, the ECU 10 determines that an open circuit failure has occurred in the second contactor 6B due to an abnormality in the second contactor drive circuit 15B, and stops the operation of the converter 5.

[0032] The converter system 1 is configured as described above. The operation and effects of the converter system 1 configured as described above will be explained later.

[0033] Before describing the operation and effects of the converter system 1 according to the embodiment, the configuration and operation of the converter system 1 according to a comparative example will be described.

[0034] 3 is a block diagram showing the functional configuration of a converter system 101 according to a comparative example. Elements that are the same as or similar to those in the converter system 1 according to the embodiment are given the same reference numerals. Explanations that overlap with those of the first embodiment will be omitted.

[0035] As shown in Fig. 3, this converter system 101 differs from the converter system 1 according to the embodiment in that it does not include the first current sensor 19A and the second current sensor 19B (see Fig. 1), but is otherwise configured similarly. Because this converter system 101 does not include the first current sensor 19A and the second current sensor 19B, it cannot detect the currents of the first contactor drive circuit 15A and the second contactor drive circuit 15B. In other words, the ECU 10 of the converter system 101 cannot detect the contactor drive currents flowing from the first contactor drive circuit 15A and the second contactor drive circuit 15B to the electromagnetic coils 14 of the corresponding contactors 6.

[0036] Therefore, in this converter system 101, the ECU 10 does not stop the operation of the converter 5 based on the detection results of the first current sensor 19A and the second current sensor 19B detected during operation of the converter 5. Therefore, if power is not supplied from one of the first contactor drive circuit 15A and the second contactor drive circuit 15B to the corresponding contactor 6, causing an open fault in which the contactor 6 is unintentionally opened, the output voltage of the converter 5 becomes excessively high.

[0037] The operation of the converter system 101 at this time will be described with reference to Fig. 4. Fig. 4 is a time chart showing the operation of the converter system 101 according to the comparative example. Note that the operation of the converter system 101 is the same whether an open fault occurs in the first contactor 6A or the second contactor 6B, and therefore, in the following description, the first and second contactors will not be distinguished and will be referred to as the contactor 6. As shown in the figure, at time t11, an open fault occurs in which the contactor 6 is unintentionally opened.

[0038] If the capacitance of the capacitor provided in converter 5 is small, the output voltage of converter 5 increases rapidly, as indicated by the dashed line, and exceeds the overvoltage threshold. When the output voltage exceeds the overvoltage threshold, ECU 10 stops the operation of converter 5. That is, ECU 10 starts processing to stop the operation of converter 5. However, as described above, there is a shutdown delay between the time when the output voltage of converter 5 exceeds the overvoltage threshold and the actual completion of the shutdown operation of converter 5. During this time, converter 5 continues to output voltage, causing the output voltage of converter 5 to become excessive. Therefore, the application of excessive voltage may cause damage to electronic components, including the capacitor.

[0039] On the other hand, if the capacitance of the capacitor provided in converter 5 is large, the output voltage of converter 5 increases gradually, as shown by the solid line. There is still a shutdown delay between the time when the output voltage of converter 5 exceeds the overvoltage threshold and ECU 10 stops the operation of converter 5, and the time when the shutdown operation of converter 5 is completed. However, because the output voltage rises gradually, the voltage rise during the shutdown delay period is smaller than when the capacitance of the capacitor is small. This reduces the possibility of failure of electronic components, including the capacitor. However, there is still a long time between time t11 when an open circuit failure occurs in contactor 6 and time t12 when converter 5 stops and its output voltage drops, and a voltage exceeding the overvoltage threshold is still output.

[0040] In contrast, the converter system 1 according to this embodiment operates as follows. Fig. 2 is a time chart showing the operation of the converter system 1 according to this embodiment. In this embodiment, the operation of the converter system 101 is the same regardless of whether an open fault occurs in the first contactor 6A or the second contactor 6B. Therefore, in the following description, the first and second contactors will not be distinguished from each other and will be referred to as the contactor 6.

[0041] As shown in FIG. 2, at time t1, power is no longer supplied from the first contactor drive circuit 15A and the second contactor drive circuit 15B to the corresponding contactor 6, causing an open fault in which the contactor 6 is unintentionally opened.

[0042] The ECU 10 is equipped with the first current sensor 19A and the second current sensor 19B, and is therefore able to detect the currents in the first contactor drive circuit 15A and the second contactor drive circuit 15B. That is, the ECU 10 can detect the contactor drive currents flowing from the first contactor drive circuit 15A and the second contactor drive circuit 15B to the electromagnetic coils 14 of the corresponding contactors 6. Therefore, at time t1, the ECU 10 determines that an open circuit failure has occurred in the contactor 6 and stops the converter 5.

[0043] The ECU 10 determines that an open circuit failure has occurred in the contactor 6 and stops the converter 5 at time t1, after which the converter 5 stops after a predetermined delay, and the output voltage of the converter 5 drops at time t2 when the converter 5 stops. Meanwhile, the ECU 10 stops the operation of the converter 5 at time t1 when the first current sensor 19A and the second current sensor 19B no longer detect the contactor drive current while the converter 5 is operating. Therefore, whether the capacitance of the capacitor is large (solid line) or small (dashed line), the output voltage of the converter 5 does not become higher than in the comparative example. This reduces the possibility of electronic components, including the capacitor, failing due to the application of excessive voltage.

[0044] In this way, when converter 5 outputs current to load 3, i.e., while converter 5 is operating, ECU 10 stops the operation of converter 5 at time t2 when current sensor 19 no longer detects the contactor drive current, thereby preventing the output voltage of converter 5 from becoming excessive.

[0045] In this embodiment, the first power supply path 4 is provided with a first contactor 6A and a second contactor 6B, and the current sensor 19 includes a first current sensor 19A and a second current sensor 19B. Regardless of whether an open circuit failure occurs in either contactor 6, the ECU 10 stops the operation of the converter 5 at time t2 when the current sensor 19 on the side where the failure occurs no longer detects the contactor drive current. This prevents the output voltage of the converter 5 from becoming excessively high.

[0046] Although the description of the specific embodiment has been completed above, the present invention is not limited to the above embodiment and its modifications, and can be widely modified and implemented. For example, in the above embodiment, the load 3 is a motor or inverter for a vehicle, but the load 3 may be a drive device other than a vehicle, a drive unit of a moving body other than a vehicle, industrial machinery, or other electrical equipment. Furthermore, only one of the first contactor 6A and the second contactor 6B may be provided as the contactor 6. In this case, the ECU 10 only needs to be equipped with one corresponding current sensor 19. Furthermore, the specific configuration, arrangement, and quantity of each member and part may be modified as appropriate within the scope of the present invention. Meanwhile, not all of the components shown in the above embodiment are necessarily required, and may be selected as appropriate. [Explanation of symbols]

[0047] 1: Converter system 2: Power supply 3: Load 4: First power supply path 4A: Positive power line 4B: Negative power line 5: Converter 6: Contactor 6A: First contactor 6B: Second contactor 10: ECU (control unit) 11: Voltage detection circuit 13: Movable contact (normally open terminal) 14: Electromagnetic coil 15A: First contactor drive circuit 15B: Second contactor drive circuit 17A: First contactor power supply path 17B: Second contactor power supply path 19: Current sensor 19A: First current sensor 19B: Second current sensor 101: Converter System

Claims

1. a first power supply path connecting the power supply and the load; a converter provided in the first power supply path; a contactor provided between the converter and the load in the first power supply path, the contactor having a normally open movable contact for selectively connecting and disconnecting the first power supply path and an electromagnetic coil for driving the movable contact; a contactor drive circuit electrically connected to the electromagnetic coil and configured to drive the contactor; a current sensor that detects a contactor drive current flowing from the contactor drive circuit to the electromagnetic coil; a control device that controls the converter and controls the contactor drive circuit so as to supply power to the electromagnetic coil to close the contactor when the converter is operating and to stop supplying power to the electromagnetic coil to open the contactor when the converter is stopped; The control device is configured to stop operation of the converter when the current sensor no longer detects current while the converter is operating.

2. the contactors include a first contactor provided on a positive power line of the first power supply path and a second contactor provided on a negative power line of the first power supply path; the contactor drive circuit includes a first contactor drive circuit that drives the first contactor and a second contactor drive circuit that drives the second contactor; 2. The converter system according to claim 1, wherein the current sensor includes a first current sensor that detects a contactor drive current flowing from the first contactor drive circuit to the electromagnetic coil of the first contactor, and a second current sensor that detects a contactor drive current flowing from the second contactor drive circuit to the electromagnetic coil of the second contactor.

3. A converter driving method in a converter system, comprising: The converter system comprises: a first power supply path connecting the power supply and the load; a converter provided in the first power supply path; a contactor provided between the converter and the load in the first power supply path, the contactor having a normally open movable contact for selectively connecting and disconnecting the first power supply path and an electromagnetic coil for driving the movable contact; a contactor drive circuit electrically connected to the electromagnetic coil and configured to drive the contactor; a current sensor that detects a contactor drive current flowing from the contactor drive circuit to the electromagnetic coil, controlling the contactor drive circuit to supply power to the electromagnetic coil to close the contactor when the converter is operating, and to stop supplying power to the electromagnetic coil to open the contactor when the converter is stopped; A converter driving method comprising: stopping operation of the converter when the current sensor no longer detects a current during operation of the converter.

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