Power circuit

Abstract

Determine whether or not there is an abnormality in the voltage divider circuit. [Solution] The power supply circuit 30 includes a capacitor 33 connected in parallel to the power supply 11, a processor 61, and a voltage divider circuit 40. The voltage divider circuit 40 includes first detection resistors 42 and 43 connected to the power supply 11, a second detection resistor 44 connected in series with the first detection resistors 42 and 43, a discharge resistor 52 connected to the power supply 11, and a voltage divider resistor 53 connected in series with the discharge resistor 52 and having a resistance value smaller than that of the discharge resistor 52. The processor 61 determines whether or not there is an abnormality in the voltage divider circuit 40 based on a first voltage input from a first connection point P1, which is the connection point between the first detection resistors 42 and 43 and the second detection resistor 44, and a second voltage input from a second connection point P2, which is the connection point between the discharge resistor 52 and the voltage divider resistor 53.

Description

Technical Field

[0001] This disclosure relates to a power supply circuit.

Background Art

[0002] The power supply circuit disclosed in Patent Document 1 includes a voltage dividing circuit that divides the voltage input from a power supply, and a control circuit. The voltage dividing circuit is formed by connecting two resistors in series. The connection point of the two resistors is connected to the control circuit. The control circuit measures the voltage input from the power supply from the voltage input from the connection point.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There are cases where it is required to detect an abnormality in the voltage dividing circuit in a power supply circuit.

Means for Solving the Problems

[0005] The power supply circuit for solving the above problems includes a capacitor connected in parallel to a power supply, a processor, and a voltage dividing circuit that divides an input voltage input from the power supply and outputs it to the processor. The voltage dividing circuit includes a first detection resistor connected to the power supply, a second detection resistor connected in series to the first detection resistor, a discharge resistor connected to the power supply, and a voltage dividing resistor connected in series to the discharge resistor and having a resistance value smaller than the resistance value of the discharge resistor. The processor determines whether an abnormality has occurred in the voltage dividing circuit based on a first voltage input from a first connection point that is a connection point of the first detection resistor and the second detection resistor, and a second voltage input from a second connection point that is a connection point of the discharge resistor and the voltage dividing resistor.

[0006] The processor receives a first voltage and a second voltage. The first voltage is a voltage corresponding to the ratio of the resistance value of the first detection resistor to the resistance value of the second detection resistor. The second voltage is a voltage corresponding to the ratio of the resistance value of the discharge resistor to the resistance value of the voltage divider resistor. Since the first voltage and the second voltage are correlated, the processor can determine whether or not there is an abnormality in the voltage divider circuit based on the first voltage and the second voltage.

[0007] In the above power supply circuit, the resistance value of the voltage divider resistor may be less than 1 / 100 of the resistance value of the discharge resistor. With respect to the power supply circuit described above, the processor may determine whether or not an abnormality has occurred in the voltage divider circuit based on a map that defines a normal range corresponding to the first voltage and the second voltage.

[0008] Regarding the power supply circuit described above, the power supply supplies power to an electric compressor used in a vehicle air conditioning system, and comprises a relay connected to the power supply and an on / off control unit that controls the opening and closing of the relay. The processor may cause the on / off control unit to open the relay if an abnormality occurs in the voltage divider circuit. [Effects of the Invention]

[0009] According to the present invention, it is possible to determine whether or not an abnormality has occurred in the voltage divider circuit. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a circuit diagram of the power supply circuit. [Figure 2] Figure 2 is a schematic diagram of the map. [Modes for carrying out the invention]

[0011] One embodiment of a power supply circuit will be described. As shown in Figure 1, the vehicle 10 includes a power supply 11, an electric compressor 21, and a power supply circuit 30.

[0012] Power supply 11 is a DC power supply. Power supply 11 is, for example, a battery. Power supply 11 outputs a voltage of, for example, 400[V] to 900[V]. Power supply 11 supplies power to the electric compressor 21.

[0013] The electric compressor 21 comprises a power converter 22, an electric motor 23, and a compression unit 24. The electric compressor 21 may be used in a vehicle air conditioning system. In this case, the electric compressor 21 compresses and discharges a refrigerant as a fluid.

[0014] The power converter 22 converts and outputs the power input from the power supply 11. The power converter 22 is an inverter that converts the DC power input from the power supply 11 into AC power and outputs it. The power converter 22 is equipped with a switching element, and the switching operation of the switching element converts the DC power into AC power. The AC power output from the power converter 22 is supplied to the electric motor 23. The AC power is three-phase AC.

[0015] The electric motor 23 is a three-phase motor driven by AC power supplied from the power converter 22. The electric motor 23 comprises, for example, three coils connected in a star configuration. The compression unit 24 is driven by an electric motor 23. The compression unit 24 compresses and discharges the fluid. The compression unit 24 can be of any type, such as scroll type, piston type, or vane type.

[0016] <Power circuit> The power supply circuit 30 is located between the power supply 11 and the power converter 22. The power supply circuit 30 includes a relay 31 and an on / off control unit 32. The relay 31 is connected in series with the power supply 11. The opening and closing of the relay 31 is controlled by the on / off control unit 32. The on / off control unit 32 is, for example, an electronic control device installed in the vehicle 10.

[0017] The power supply circuit 30 includes a capacitor 33, a voltage divider circuit 40, a processor 61, and a storage medium 62. The capacitor 33 is connected in parallel to the power supply 11. The capacitor 33 is a smoothing capacitor.

[0018] The voltage dividing circuit 40 includes a voltage detection circuit 41. The voltage detection circuit 41 is connected in parallel to the power supply 11. The voltage detection circuit 41 includes first detection resistors 42, 43 connected to the power supply 11 and a second detection resistor 44 connected in series to the first detection resistors 42, 43. The resistance values R1 of the first detection resistors 42, 43 and the resistance value R2 of the second detection resistor 44 may be the same or different. The number of the first detection resistors 42, 43 may be one or more. When there are a plurality of the first detection resistors 42, 43, the resistance value R1 of the first detection resistors 42, 43 means the combined resistance of the plurality of first detection resistors 42, 43. In the example shown in FIG. 1, there are two first detection resistors 42, 43. The number of the second detection resistors 44 may be one or more. When there are a plurality of the second detection resistors 44, the resistance value R2 of the second detection resistors 44 means the combined resistance of the plurality of second detection resistors 44. In the example shown in FIG. 1, there is one second detection resistor 44.

[0019] A first connection point P1, which is the connection point between the first detection resistors 42, 43 and the second detection resistor 44, is connected to the processor 61. A voltage corresponding to the voltage division ratio, which is the ratio of the resistance value R1 of the first detection resistors 42, 43 to the resistance value R2 of the second detection resistor 44, is input to the processor 61. The first detection resistors 42, 43 are resistance elements on the higher potential side than the first connection point P1. The second detection resistor 44 is a resistance element on the lower potential side than the first connection point P1.

[0020] The voltage division ratio between the first detection resistors 42 and 43 and the second detection resistor 44 is set such that the first voltage V1 input from the first connection point P1 to the processor 61 becomes a voltage recognizable by the processor 61. The voltage recognizable by the processor 61 is, for example, a voltage of 5 [V] or less. The first voltage V1 can be expressed as resistance value R2 × input voltage Vin / (resistance value R1 + resistance value R2). The input voltage Vin is the voltage input from the power supply 11 to the power supply circuit 30. The voltage division ratio between the first detection resistors 42 and 43 and the second detection resistor 44 is hereinafter referred to as the first voltage division ratio as appropriate.

[0021] The voltage division circuit 40 includes a discharge circuit 51. The discharge circuit 51 is connected in parallel to the power supply 11. The discharge circuit 51 includes a discharge resistor 52 connected to the power supply 11 and a voltage division resistor 53 connected in series to the discharge resistor 52 and having a resistance value R4 smaller than the resistance value R3 of the discharge resistor 52. The discharge resistor 52 may be one or a plurality. When there are a plurality of discharge resistors 52, the resistance value R3 of the discharge resistor 52 means the combined resistance of the plurality of discharge resistors 52. In the example shown in FIG. 1, the discharge resistor 52 is one. The voltage division resistor 53 may be one or a plurality. When there are a plurality of voltage division resistors 53, the resistance value R4 of the voltage division resistor 53 means the combined resistance of the plurality of voltage division resistors 53. In the example shown in FIG. 1, the voltage division resistor 53 is one.

[0022] The discharge circuit 51 is a circuit for discharging the capacitor 33 when the power supply 11 is disconnected from the power supply circuit 30. The resistance value R3 of the discharge resistor 52 is set to comply with standards such as FMVSS (Federal Motor Vehicle Safety Standards). The resistance value R3 of the discharge resistor 52 is set such that, for example, the capacitor 33 discharges from the state of the maximum voltage to 60 [V] or less in 5 seconds or less. The maximum voltage of the capacitor 33 varies depending on the voltage output from the power supply 11.

[0023] The second connection point P2, which is the connection point between the discharge resistor 52 and the voltage divider resistor 53, is connected to the processor 61. A voltage corresponding to the voltage division ratio, which is the ratio of the resistance value R3 of the discharge resistor 52 to the resistance value R4 of the voltage divider resistor 53, is input to the processor 61. The discharge resistor 52 is a resistive element on the higher potential side than the second connection point P2. The voltage divider resistor 53 is a resistive element on the lower potential side than the second connection point P2. The voltage division ratio between the discharge resistor 52 and the voltage divider resistor 53 is appropriately referred to as the second voltage division ratio.

[0024] The resistance value R4 of the voltage divider resistor 53 is set so that the second voltage V2 input from the second connection point P2 to the processor 61 becomes a voltage that the processor 61 can recognize. The processor 61 is, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or a DSP (Digital Signal Processor). The processor 61 is configured to communicate with the switching control unit 32.

[0025] The processor 61 controls the power converter 22 according to the input voltage Vin input from the power supply 11. The input voltage Vin can be measured, for example, from the first voltage V1 input from the first connection point P1. The input voltage Vin can be expressed as first voltage V1 × (resistance value R1 + resistance value R2) / resistance value R2. The processor 61 controls the duty cycle of the switching elements in the power converter 22 according to the input voltage Vin and the target rotational speed of the electric motor 23. In this way, the processor 61 controls the voltage output from the power converter 22 to the electric motor 23.

[0026] <Detection of abnormalities in the voltage divider circuit> The processor 61 determines whether or not there is an abnormality in the voltage divider circuit 40. An abnormality in the voltage divider circuit 40 includes an abnormality in the voltage detection circuit 41 and an abnormality in the discharge circuit 51.

[0027] An abnormality in the voltage detection circuit 41 is, for example, the deterioration of at least one of the first detection resistors 42, 43 and the second detection resistor 44. When at least one of the first detection resistors 42, 43 and the second detection resistor 44 deteriorates, the first voltage division ratio changes due to the change in resistance values ​​R1 and R2. This may prevent the processor 61 from correctly measuring the input voltage Vin. If the processor 61 cannot correctly measure the input voltage Vin, it may not be able to properly control the switching elements of the power converter 22. This may increase losses in the power converter 22.

[0028] An abnormality in the discharge circuit 51 is, for example, an open circuit in the discharge resistor 52. When an open circuit occurs in the discharge resistor 52, it may become impossible to discharge the capacitor 33. The processor 61 determines whether or not an abnormality has occurred in the voltage divider circuit 40 based on the first voltage V1 and the second voltage V2. In this embodiment, the processor 61 determines whether or not an abnormality has occurred in the voltage divider circuit 40 based on the map M. The map M is stored in a storage medium 62 that can be read by the processor 61. The storage medium 62 may be a ROM (Read Only Memory) or a flash memory or the like whose stored contents can be rewritten.

[0029] As shown in Figure 2, map M defines a normal range A1 in correspondence with the first voltage V1 and the second voltage V2. The processor 61 determines that there is no abnormality in the voltage divider circuit 40 if the intersection of the first voltage V1 input from the first connection point P1 and the second voltage V2 input from the second connection point P2 is within the normal range A1. The processor 61 determines that there is an abnormality in the voltage divider circuit 40 if the intersection of the first voltage V1 input from the first connection point P1 and the second voltage V2 input from the second connection point P2 is outside the normal range A1.

[0030] Map M is configured to compare the difference between the input voltage Vin applied to the voltage detection circuit 41 and the input voltage Vin applied to the discharge circuit 51. Although the input voltage Vin applied to the voltage detection circuit 41 and the input voltage Vin applied to the discharge circuit 51 are the same value, a difference arises between the first voltage V1 and the second voltage V2 due to the difference between the first voltage division ratio and the second voltage division ratio. Therefore, Map M is configured to compare the value obtained by converting the first voltage V1 to input voltage Vin and the value obtained by converting the second voltage V2 to input voltage Vin, according to the difference between the first voltage division ratio and the second voltage division ratio.

[0031] For example, suppose that when the input voltage Vin is 400[V], the first voltage divider ratio is set so that the first voltage V1 is 4[V], and the second voltage divider ratio is set so that the second voltage V2 is 3[V]. In this case, the map M is set so that the 4[V] of the first voltage V1 corresponds to 400[V], and the 3[V] of the second voltage V2 corresponds to 400[V]. As a result, when the first voltage V1 is 4[V] and the second voltage V2 is 3[V], it is possible to determine from the intersection of these values ​​whether or not there is an abnormality in the voltage divider circuit 40.

[0032] If the resistance values ​​R1 of the first detection resistors 42 and 43 and the resistance value R2 of the second detection resistor 44 change due to degradation, a difference will occur between the first voltage division ratio assumed in map M and the actual first voltage division ratio, causing the intersection point of the first voltage V1 and the second voltage V2 to fall outside the normal range A1. If an open circuit abnormality occurs in the discharge resistor 52, the input voltage Vin will no longer be applied to the discharge circuit 51, causing the intersection point of the first voltage V1 and the second voltage V2 to fall outside the normal range A1. Therefore, the processor 61 can use map M to determine whether or not an abnormality has occurred in the voltage division circuit 40. The normal range A1 is set so that an abnormality in the voltage division circuit 40 is not determined due to measurement errors. Also, if the resistance values ​​R1 of the first detection resistors 42 and 43 and the resistance value R2 of the second detection resistor 44 change due to degradation, the resistance values ​​R1 of the first detection resistors 42 and 43 and the resistance value R2 of the second detection resistor 44 will change gradually. The normal range A1 may be set as a range that allows for changes in the resistance values ​​R1 of the first detection resistors 42 and 43 and the resistance value R2 of the second detection resistor 44.

[0033] If the processor 61 determines that an abnormality has occurred in the voltage divider circuit 40, it notifies the switching control unit 32, causing the switching control unit 32 to open the relay 31. [Effects of this embodiment] (1) The processor 61 receives a first voltage V1 and a second voltage V2 as inputs. The first voltage V1 is a voltage corresponding to the first voltage division ratio. The second voltage V2 is a voltage corresponding to the second voltage division ratio. The same voltage, i.e., the input voltage Vin, is applied to the voltage detection circuit 41 and the discharge circuit 51. Therefore, the first voltage V1 and the second voltage V2 are values ​​corresponding to the input voltage Vin and are correlated with each other. In this embodiment, the correlation between the first voltage V1 and the second voltage V2 is represented as a map M in relation to the input voltage Vin. Therefore, the processor 61 can determine whether or not an abnormality has occurred in the voltage division circuit 40 based on the first voltage V1 and the second voltage V2.

[0034] (2) The resistance value R4 of the voltage divider resistor 53 is less than 1 / 100 of the resistance value R3 of the discharge resistor 52. This prevents the second voltage V2 input to the processor 61 from becoming excessively high.

[0035] (3) The processor 61 determines whether or not there is an abnormality in the voltage divider circuit 40 based on a map M which defines a normal range A1 in association with the first voltage V1 and the second voltage V2. Since the processor 61 can determine whether or not there is an abnormality in the voltage divider circuit 40 by referring to map M, the processing load can be reduced.

[0036] (4) If an abnormality occurs in the voltage divider circuit 40, the processor 61 instructs the switching control unit 32 to open the relay 31. As a result, the power supply 11 is cut off from the power supply circuit 30, and the electric compressor 21 stops.

[0037] If a malfunction occurs in the voltage detection circuit 41, the power loss in the power converter 22 may increase. By stopping the electric compressor 21 when a malfunction occurs in the voltage detection circuit 41, the increase in losses in the power converter 22 can be suppressed.

[0038] If an open circuit abnormality occurs in the discharge resistor 52, the capacitor 33 may not be able to discharge. By stopping the electric compressor 21 when an abnormality occurs in the discharge circuit 51, it is possible to prevent the electric compressor 21 from continuing to operate while the capacitor 33 cannot be discharged.

[0039] (5) The discharge resistor 52, which is provided to discharge the capacitor 33, is used to determine whether or not there is an abnormality in the voltage divider circuit 40. Since the discharge resistor 52 can also be used as a voltage divider resistor, the number of components can be reduced compared to when a separate voltage divider resistor is provided in addition to the discharge resistor 52.

[0040] [Example of changes] The embodiment can be implemented with the following modifications. The embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0041] ○The processor 61 may issue a warning to the occupants of the vehicle 10 if an abnormality occurs in the voltage divider circuit 40. The warning may be given by an alarm that uses sound, light, etc. The warning may also be given by displaying it on a display unit visible to the occupants of the vehicle 10. For example, the warning may be given by displaying a message on the display unit prompting the occupants to go to a dealer. When issuing a warning to the occupants of the vehicle 10, the processor 61 may or may not cause the opening / closing control unit 32 to open the relay 31.

[0042] ○The processor 61 may determine whether or not there is an abnormality in the voltage divider circuit 40 based on the difference between the input voltage Vin calculated from the first voltage V1 and the input voltage Vin calculated from the second voltage V2. The input voltage Vin can be expressed as first voltage V1 × (resistance R1 + resistance R2) / resistance R2. Therefore, by knowing the resistance values ​​R1 and R2 in advance, the input voltage Vin can be calculated using the first voltage V1. The input voltage Vin can be expressed as second voltage V2 × (resistance R3 + resistance R4) / resistance R4. Therefore, by knowing the resistance values ​​R3 and R4 in advance, the input voltage Vin can be calculated using the second voltage V2. The processor 61 determines that there is an abnormality in the voltage divider circuit 40 if the difference between the input voltage Vin calculated from the first voltage V1 and the input voltage Vin calculated from the second voltage V2 is greater than or equal to a threshold. The processor 61 determines that there is no abnormality in the voltage divider circuit 40 if the difference between the input voltage Vin calculated from the first voltage V1 and the input voltage Vin calculated from the second voltage V2 is less than a threshold. The threshold is set so that the voltage divider circuit 40 is not judged to be abnormal due to measurement errors. The resistance values ​​R1, R2, R3, and R4 can be stored, for example, in a storage medium 62.

[0043] ○The processor 61 may determine whether or not there is an abnormality in the voltage divider circuit 40 based on the difference between the first voltage V1 and the second voltage V2. For example, if there is no abnormality in the voltage divider circuit 40 and the range of possible differences between the first voltage V1 and the second voltage V2 is known in advance, the processor 61 may determine that there is an abnormality in the voltage divider circuit 40 if the difference between the first voltage V1 and the second voltage V2 exceeds this range.

[0044] ○The resistance value R4 of the voltage divider resistor 53 only needs to be able to make the second voltage V2 a voltage that the processor 61 can recognize, and may be a value of 1 / 100 or more of the resistance value R3 of the discharge resistor 52. [Explanation of Symbols]

[0045] A1...Normal range, M...Map, P1...First connection point, P2...Second connection point, 11...Power supply, 21...Electric compressor, 31...Relay, 32...Switching control unit, 33...Capacitor, 40...Voltage divider circuit, 42,43...First detection resistor, 44...Second detection resistor, 52...Discharge resistor, 53...Voltage divider resistor, 61...Processor.

Claims

1. A capacitor connected in parallel with the power supply, Processor and The system includes a voltage divider circuit that divides the input voltage received from the power supply and outputs it to the processor, The aforementioned voltage divider circuit is A first detection resistor connected to the power supply, A second detection resistor connected in series with the first detection resistor, A discharge resistor connected to the aforementioned power supply, The system comprises a voltage divider resistor connected in series with the discharge resistor and having a resistance value smaller than the resistance value of the discharge resistor, The processor is a power supply circuit that determines whether or not an abnormality has occurred in the voltage divider circuit based on a first voltage input from a first connection point which is the connection point between the first detection resistor and the second detection resistor, and a second voltage input from a second connection point which is the connection point between the discharge resistor and the voltage divider resistor.

2. The power supply circuit according to claim 1, wherein the resistance value of the voltage divider resistor is less than 1 / 100 of the resistance value of the discharge resistor.

3. The power supply circuit according to claim 1, wherein the processor determines whether or not an abnormality has occurred in the voltage divider circuit based on a map that defines a normal range in correspondence with the first voltage and the second voltage.

4. The aforementioned power supply provides power to an electric compressor used in a vehicle air conditioning system. A relay connected to the aforementioned power supply, The system comprises an opening / closing control unit that controls the opening and closing of the relay, The power supply circuit according to claim 1, wherein the processor causes the switching control unit to open the relay if an abnormality occurs in the voltage divider circuit.

Images