Power conversion device

Abstract

To provide a power conversion device capable of quickly and safely performing protection operation when abnormality occurs.SOLUTION: An abnormality control unit includes a first control unit and a second control unit. When abnormality occurs, second control (SD control) in the second control unit is quickly performed without waiting for performance determination of first control (ASC control) in the first control unit. After an initial period ends, first control (ASC control) with high safety is performed based on performance determination in the first control unit. By combining two protection operations, namely, rapid SD control and highly safe ASC control performed based on an appropriate determination result after the initial period ends, both speed and safety of the protection operation are achieved.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a power conversion device. [Background technology]

[0002] When it is determined that an abnormality has occurred in the power conversion device, two protective actions are known to protect the power conversion device and the motor: active short circuit control (ASC control), which forcibly switches either the upper arm or the lower arm to a conductive state and the other to a non-conductive state, and shutdown control (SD control), which forcibly switches both the upper arm and the lower arm to a non-conductive state.When SD control is performed, so-called regeneration occurs, in which a back electromotive force or an induced current is generated in the windings due to the rotation of the rotor that makes up the motor.This can cause problems such as failure of the power conversion device or other connected equipment, or unstable vehicle behavior due to a sudden stop of the rotor.Therefore, ASC control is given priority except in cases where it is not possible to perform ASC control.

[0003] For example, Patent Document 1 discloses a technology in which a circuit that performs ASC control and a circuit that performs SD control are provided separately from the circuit that generates switching control signals for the upper arm and the lower arm, and the circuit that performs ASC control is located closer to the upper arm and the lower arm, so that ASC control takes priority over SD control.

[0004] However, although ASC control is considered to be safer than SD control as mentioned above, if the arm to be switched to the conductive state is selected incorrectly, not only will the desired ASC control not be achieved, but in some cases there is a concern that it may even exacerbate an abnormal state. For this reason, it is important to correctly select the arm to be switched to the conductive state.

[0005] To address this problem, for example, in Patent Document 2, a matrix circuit is provided that determines and selects the arm to be forcibly switched to a conductive state based on the state of the upper arm or lower arm in which an abnormality has occurred, separate from the circuit that generates the switching control signals for the upper arm and the lower arm. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5547559 [Patent Document 2] JP 2022-48606 A Summary of the Invention [Problem to be solved by the invention]

[0007] Power conversion devices are precision equipment, and in particular automotive power conversion devices, there are a wide variety of abnormal conditions in the upper and lower arms. For this reason, ASC control requires complex and time-consuming calculations to analyze the abnormal conditions of the arms and accurately determine which arms to switch to a conductive state. Therefore, prioritizing ASC control, which is considered to be highly safe, raises concerns that it may take a long time for protective action to be taken after an abnormality occurs.

[0008] An object of the present disclosure is to provide a power conversion device that can quickly and safely perform a protective operation when an abnormality occurs. [Means for solving the problem]

[0009] The power conversion device according to the present disclosure comprises: an abnormality control unit that outputs a first control signal to the drive unit to turn on one of the upper arm and the lower arm and turn off the other, or outputs a second control signal to the drive unit to turn off both the upper arm and the lower arm, The abnormality control unit a first control unit that selectively determines whether to make the upper arm or the lower arm conductive based on an abnormality signal and outputs a first control signal; The control device further includes a second control unit that is disposed on a control signal path from the first control unit to the drive unit, and that outputs a second control signal without transmitting an output signal from the first control unit to the drive unit during an initial period from the input of an abnormality signal, and that transmits an output signal from the first control unit to the drive unit after the initial period has ended. Here, the second control corresponds to SD control, and the first control corresponds to ASC control. [Effects of the Invention]

[0010] According to the power conversion device of the present disclosure, when an abnormality occurs, the second control unit quickly performs the second control corresponding to the SD control without waiting for the first control unit to determine whether to perform the first control corresponding to the ASC control. After the initial period ends, the first control corresponding to the highly safe ASC control is performed based on the determination by the first control unit.

[0011] In this way, by combining two protective operations, namely, SD control, which is performed quickly, and ASC control, which is highly safe and is performed based on appropriate judgment results after the initial period has ended, the power conversion device of the present disclosure can achieve both quick and safe protective operations. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing a power conversion device according to a first embodiment. [Figure 2] 3 is a block diagram showing an abnormality control unit according to the first embodiment. FIG. [Figure 3] 5 is a flowchart showing the operation of an abnormality control unit according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiment 1 A power conversion device according to embodiment 1 will be described with reference to the drawings. In this embodiment, a rotating electric machine M provided in an automobile (not shown) is to be controlled.

[0014] <Power conversion device> As shown in Fig. 1, the power conversion device 1 is connected to a rotating electric machine M that operates on three-phase AC, and includes a drive unit 2, a control unit 3, an abnormality detection unit 4, and an abnormality control unit 5. Reference numeral 6 denotes a DC power supply, which is mounted on an automobile (not shown). In this configuration, the abnormality detection unit 4 is provided outside the drive unit 2, but this is not limiting. For example, the abnormality detection unit 4 may be provided inside the drive unit 2 or integrally with the drive unit 2.

[0015] <Drive unit> The drive unit 2 has an upper arm 7 configured with three switching elements 7a corresponding to the U, V, and W phases, and a lower arm 8 similarly configured with three switching elements 8a. The drive unit 2 also has an upper drive circuit 9 that drives the upper arm 7 and a lower drive circuit 10 that drives the lower arm 8. A DC power supply 6 that serves as a power source for the rotating electric machine M is connected in parallel to the high potential side of the upper arm 7 and the low potential side of the lower arm 8. Here, the switching elements 7a and 8a are transistors made of wide bandgap semiconductors such as silicon (Si), silicon carbide (SiC), or gallium nitride (GaN). The high-side drive circuit 9 and the low-side drive circuit 10 are generally used, and detailed description thereof will be omitted.

[0016] <Control unit> The control unit 3 controls the drive unit 2, and in particular, when the drive unit 2 enters an abnormal state, it performs protective operations such as ASC control and SD control on the drive unit 2. The abnormal state of the drive unit 2 is detected by an abnormality detection unit 4. In the abnormal state, an abnormality control unit 5 included in the control unit 3 performs a first control equivalent to ASC control and a second control equivalent to SD control as protective operations. In the following description of this embodiment, the first control will be referred to as ASC control and the second control will be referred to as SD control.

[0017] In a normal state, the switching of the six switching elements 7a, 8a is individually controlled by six drive signals VUH, VVH, VWH, VUL, VVL, and VWL output from the control device 3 to the drive unit 2. The drive signal VUH controls the switching element 7a corresponding to the U phase of the upper arm 7, the drive signal VVH controls the switching element 7a corresponding to the V phase of the upper arm 7, the drive signal VWH controls the switching element 7a corresponding to the W phase of the upper arm 7, the drive signal VUL controls the switching element 8a corresponding to the U phase of the lower arm 8, the drive signal VVL controls the switching element 8a corresponding to the V phase of the lower arm 8, and the drive signal VWL controls the switching element 8a corresponding to the W phase of the lower arm 8. The control in a normal state is a general one according to the desired characteristics, functions, etc., and therefore a detailed description thereof will be omitted.

[0018] In an abnormal state, the abnormality detection unit 4 detects the location and content of the abnormality and outputs abnormality signals FLT1, FLT2, FLT3, and FLT4. The abnormality signal FLT1 indicates an abnormality in which the upper arm 7 is fixed in a non-conductive state. The abnormality signal FLT2 indicates an abnormality in which the upper arm 7 is fixed in a conductive state. The abnormality signal FLT3 indicates an abnormality in which the lower arm 8 is fixed in a non-conductive state. The abnormality signal FLT4 indicates an abnormality in which the lower arm 8 is fixed in a conductive state.

[0019] The abnormality control unit 5 outputs control signals ASCH and ASCL based on the abnormality signals FLT1, FLT2, FLT3, and FLT4 from the abnormality detection unit 4. The control signals ASCH and ASCL are high and low signals, respectively, and are output in four different combinations. An example of the correspondence between the state of the drive unit 2, the state of the control signals ASCH and ASCL from the abnormality control unit 5, and the control state of the upper and lower arms 7 and 8 based on these control signals ASCH and ASCL will be described with reference to Table 1 below.

[0020] [Table 1]

[0021] If the drive unit 2 is in a normal state, the abnormality detection unit 4 detects no abnormality, the control signal ASCH of the abnormality control unit 5 becomes a high signal (shown as H in Table 1), and the control signal ASCL also becomes a high signal. In this case, the control states of the upper and lower arms 7 and 8 are controlled individually for the switching elements 7a and 8a in accordance with the drive signals VUH to VWL.

[0022] If the drive unit 2 is in an abnormal state, the abnormality is detected by the abnormality detection unit 4, and based on the abnormality signals FLT1, FLT2, FLT3, and FLT4, the control signals ASCH and ASCL of the abnormality control unit 5 are output in three combinations as shown in Table 1.

[0023] When the control signal ASCH is a high signal and the control signal ASCL is a low signal (shown as L in Table 1), this corresponds to the first control signal, and ASC control is performed to make the upper arm 7 conductive and the lower arm 8 non-conductive.

[0024] When the control signal ASCH is a low signal and the control signal ASCL is a high signal, this also corresponds to the first control signal, and ASC control is performed to make the upper arm 7 non-conductive and the lower arm 8 conductive.

[0025] When the control signal ASCH is a low signal and the control signal ASCL is also a low signal, this corresponds to the second control signal, and SD control is performed to put the upper arm 7 into a non-conductive state and the lower arm 8 into a non-conductive state.

[0026] <Abnormality control section> A specific configuration of the abnormality control unit 5 will be described with reference to FIG. The abnormality control unit has a first control unit 11, a second control unit 12 arranged on a control signal path from the first control unit 11 to the drive unit 2, and an internal power supply 13.

[0027] <First control section> The first control unit 11 is composed of a switch SWH1 provided on the path of the control signal ASCH connected to the internal power supply 13, a switch SWL1 provided on the path of the control signal ASCL connected to the internal power supply 13, and a logic unit 14 that controls the switches SWH1 and SWL1 individually based on the states of the abnormality signals FLT1 to FLT4. Furthermore, the logic unit 14 controls switches SWH3 and SWL3 of the second control unit 12, which will be described later.

[0028] If the drive unit 2 is in a normal state, none of the abnormality signals FLT1 to FLT4 are input to the logic unit 14. In this case, the logic unit 14 turns on both the switch SWH1 and the switch SWL1. This means that, as output signals from the first control unit, the control signal ASCH becomes a high signal, and the control signal ASCL also becomes a high signal.

[0029] If the drive unit 2 is in an abnormal state, one or more of the abnormality signals FLT1 to FLT4 are input to the logic unit 14. The logic unit 14 determines whether to perform ASC control based on the combination of the abnormality signals FLT1 to FLT4. When performing ASC control, it selectively determines whether to perform upper-side ASC control, in which the upper arm 7 is in a conductive state and the lower arm 8 is in a non-conductive state, or to perform lower-side ASC control, in which the upper arm 7 is in a non-conductive state and the lower arm 8 is in a conductive state.

[0030] When performing the upper ASC control, the logic unit 14 turns on the switch SWH1 and turns off the switch SWL1, which means that the output signals from the first control unit are a high signal for the control signal ASCH and a low signal for the control signal ASCL.

[0031] When performing the lower ASC control, the logic unit 14 turns off the switch SWH1 and turns on the switch SWL1, which means that the output signals from the first control unit are a low signal for the control signal ASCH and a high signal for the control signal ASCL.

[0032] The logic unit 14 turns on both switches SWH3 and SWL3 of a second control unit, which will be described later, at the timing when it outputs control signals to the switches SWH1 and SWL1 to perform ASC control (upper ASC control or lower ASC control).

[0033] The logic unit 14 may perform more complex arithmetic processing by referring to, in addition to the abnormality signals FLT1 to FLT4, other information such as the temperature, current, and voltage of the upper arm 7 and the lower arm 8. When complex arithmetic processing is required, the entire first control unit or some of its functions may be built into a microcomputer.

[0034] <Second control section> The second control unit 12 has a switch SWH2 provided on the path of the control signal ASCH from the first control unit 11 to the drive unit 2, and a switch SWL2 provided on the path of the control signal ASCL from the first control unit 11 to the drive unit 2. The second control unit 12 also has a switch SWH3 provided in parallel with the switch SWH2, and a switch SWL3 provided in parallel with the switch SWL2. The switches SWH3 and SWL3 are controlled by the logic unit 14 of the first control unit 11.

[0035] The second control unit 12 also has a NOR circuit 15 to which the abnormality signals FLT1 to FLT4 are input, and the switches SWH2 and SWL2 are controlled by the output of this NOR circuit 15. The abnormality signals FLT1 to FLT4 are low signals in the normal state and high signals in the abnormal state.

[0036] For this reason, when at least one of the abnormality signals FLT1 to FLT4 is input, the output signal of the NOR circuit 15 becomes a low signal, and both the switches SWH2 and SWL2 are turned off. This means that, ignoring the states of the switches SWH3 and SWL3, the output signals from the second control unit are that the control signal ASCH and the control signal ASCL are both low signals.

[0037] The switches SWH3 and SWL3 are controlled by the logic unit 14 of the first control unit 11, and are both turned off when the drive unit 2 is in a normal state. Even after the drive unit 2 enters an abnormal state, the switches SWH3 and SWL3 continue to be turned off until the initial period ends. Here, the timing at which the initial period ends is controlled by the logic unit 14 of the first control unit, and is the timing at which the first control unit performs ASC control (upper ASC control or lower ASC control).

[0038] When this initial period ends, the switches SWH3 and SWL3 are both turned on. In this state, regardless of whether the switches SWH2 and SWL2 are on or off, the output signal from the first control unit 11 is transmitted as is to the drive unit 2 via the switches SWH3 and SWL3.

[0039] <Operation of the entire control unit> The operation of the entire control unit when an abnormality occurs in the drive unit 2 will be described using the flowchart shown in FIG.

[0040] <Step 10, Step 11> The first control unit 11 and the second control unit 12 acquire the abnormality signals FLT1 to FLT4 input to the logic unit 14 and the NOR circuit 15, and if they detect the input of at least one of the abnormality signals, they determine that an abnormality has occurred in the drive unit.

[0041] <Step 12> If an abnormality occurs in the drive unit 2, the output of the NOR circuit 15 of the second control unit 12 switches from high to low, controlling the switches SWH2 and SWL2 to be off. The switches SWH3 and SWL3 remain off until the end of the initial period. In this case, regardless of whether the switches SWH1 and SWL1 of the first control unit 11 are on or off, the control signals ASCH and ASCL output from the abnormality control unit 5 are both low. That is, after an abnormality occurs in the drive unit 2, the second control unit 12 performs SD control without waiting for a decision by the first control unit.

[0042] This configuration is simple, consisting of the NOR circuit 15, the switch SWH2, and the switch SWL2, and does not require complicated calculations. Therefore, it is possible to quickly perform SD control, which is a protective operation, after an abnormality occurs in the drive unit 2. Although the NOR circuit 15 is used in this configuration, the present invention is not limited to this. For example, even if a logical AND circuit is used, the same control as in this configuration can be performed by setting the abnormality signals FLT1 to FLT4 to low signals in an abnormal state and high signals in a normal state.

[0043] <Step 13> The logic section 14 of the first control section 11 estimates the state of the drive section 2 based on the input of the abnormality signals FLT1 to FLT4, and determines whether or not the abnormality requires ASC control. ASC control is recommended except in cases where it is extremely impossible, but if, for example, FLT1 indicating an abnormality in which the upper arm 7 is fixed in a non-conducting state due to some factor and FLT3 indicating an abnormality in which the lower arm 8 is fixed in a non-conducting state are recognized simultaneously, it is determined that ASC control will not be performed because neither the upper arm 7 nor the lower arm 8 can be forcibly controlled to a conductive state, and the process proceeds to step 16. As a result, SD control continues without terminating it in step 15, which will be described later.

[0044] According to this configuration, the logic unit 14 analyzes and calculates the abnormal state in detail, thereby making it possible to prevent erroneous execution of ASC control. In this configuration, SD control is continued by not performing the processing of step 15 described below, but this is not limited to this. For example, SD control by the first control unit 11 may be performed by controlling the switches SWH1 and SWL1 of the first control unit 11 to be turned off and controlling the switches SWH3 and SWL3 of the second control unit to be turned on.

[0045] <Step 14, Step 14a, Step 14b> If it is determined in step 13 that an abnormality requiring ASC control has occurred, the logic unit 14 of the first control unit estimates the state of the drive unit 2 based on the input of abnormality signals FLT1 to FLT4, and selectively determines whether the upper arm 7 or the lower arm 8 should be brought into a conductive state.

[0046] For example, if only FLT1 is found, which indicates an abnormality in which the upper arm 7 is fixed in a non-conductive state, it is determined that only the lower arm 8 can be forced into a conductive state, and step 14a (switch SWH1 is turned off and switch SWL1 is turned on) is performed to place the lower arm 8 into a conductive state. For example, if only FLT2 is found, which indicates an abnormality in which the upper arm 7 is fixed in a conductive state, forcing the lower arm 8 into a conductive state may cause the upper arm 7 and the lower arm 8 to become conductive at the same time, generating an excessive short-circuit arm current and potentially destroying the driver 2. In this case, step 14b is performed to set the upper arm 7 into a conductive state (turning on switch SWH1 and turning off switch SWL1). However, at this stage, since the switch SWH2 remains off in step 12, regardless of whether the switch SWH1 and the switch SWL1 of the first control unit 11 are on or off, the control signals ASCH and ASCL output from the abnormality control unit 5 remain low signals, and SD control continues.

[0047] According to this configuration, the logic unit 14 analyzes and calculates the abnormal state in detail, so that it is possible to accurately determine the arm to be switched to the conductive state, and it is possible to implement ASC control with high safety. In this configuration, for convenience of explanation, the explanation is divided into step 13 and step 14. However, when actually configuring the calculation process, the determination of whether to execute ASC control and the determination of which of the upper arm 7 and the lower arm 8 should be brought into a conductive state may be performed in parallel or simultaneously as calculation processes.

[0048] <Step 15> When the ASC control is performed in step 14a or step 14b, i.e., when the control of the switches SWH1 and SWL1 is performed, the switches SWH3 and SWL3 are turned on. This timing marks the end of the initial period. In this state, regardless of whether the switches SWH2 and SWL2 are on or off, the output signal from the first control unit 11 is transmitted as is to the drive unit 2 via the switches SWH3 and SWL3.

[0049] As a result, the drive unit 2 switches from SD control to lower ASC control or upper ASC control based on step 14a or step 14b.

[0050] According to this configuration, the logic unit 14 turns on the switches SWH3 and SWL3, so that the transition to ASC control can be made after a determination result regarding the implementation of ASC control has been reliably obtained, thereby enabling safer ASC control to be performed.

[0051] In this configuration, the switches SWH3 and SWL3 are turned on by a signal from the logic unit 14, but this is not limiting. For example, a timer unit may be provided to turn on the switches SWH3 and SWL3 after a set time that is longer than the time required to determine whether or not to perform ASC control has elapsed. The switch SWH3 and the switch SWL3 may be turned on.

[0052] <Step 16> It is determined whether the abnormality in the drive unit 2 has been resolved, and if it has not been resolved, the process returns to step 13 to continue ASC control. If the abnormality has been resolved, the process returns to normal operation and returns to step 10. Note that the configuration of step 16 is not limited to this. For example, the ASC control may be continued regardless of whether the abnormality has been resolved or not.

[0053] Although exemplary embodiments and examples are described in this disclosure, the features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this disclosure specification. For example, this includes cases where at least one component is modified, added, or omitted, and even cases where at least one component is extracted and combined with components of other embodiments. [Explanation of symbols]

[0054] 1: power conversion device, 2: drive unit, 3: control unit, 4: abnormality detection unit, 5: abnormality control unit, 7: upper arm, 7a: switching element, 8: lower arm, 8a: switching element, 11: first control unit, 12: second control unit

Claims

1. a drive unit including an upper arm and a lower arm each configured with a switching element, and an upper drive circuit and a lower drive circuit for driving the upper arm and the lower arm, respectively; a control unit that controls the drive unit; an abnormality detection unit that detects an abnormality in the drive unit and outputs an abnormality signal; an abnormality control unit that, when the abnormality signal is input to the control unit, outputs a first control signal to the drive unit, which causes one of the upper arm and the lower arm to be in a conductive state and the other to be in a non-conductive state, or outputs a second control signal to the drive unit, which causes both the upper arm and the lower arm to be in a non-conductive state; The abnormality control unit a first control unit that selectively determines whether to bring the upper arm or the lower arm into a conductive state based on the abnormality signal and outputs a first control signal; a second control unit that is arranged on a control signal path from the first control unit to the drive unit, that outputs a second control signal without transmitting an output signal from the first control unit to the drive unit during an initial period from the input of the abnormal signal, and that transmits an output signal from the first control unit to the drive unit after the end of the initial period.

2. the abnormality signals include at least a first signal indicating an abnormality in which the upper arm is fixed in a non-conductive state, a second signal indicating an abnormality in which the upper arm is fixed in a conductive state, a third signal indicating an abnormality in which the lower arm is fixed in a non-conductive state, and a fourth signal indicating an abnormality in which the lower arm is fixed in a conductive state; the first control unit, when at least one of the first signal to the fourth signal is input, selectively determines whether to make the upper arm or the lower arm conductive based on a combination of the first signal to the fourth signal, and outputs the first control signal; The power conversion device according to claim 1, characterized in that the second control unit outputs the second control signal when at least one of the first signal to the fourth signal is input, regardless of the combination of the first signal to the fourth signal.

3. 3. The power conversion device according to claim 1, wherein the second control unit ends the initial period at a timing when the first control signal is output from the first control unit in response to a signal from the first control unit.

4. 3. The power conversion device according to claim 1, wherein the second control unit has a timer unit, and the first control unit makes a determination based on the input of the abnormality signal, and the initial period ends after a set time that is longer than the time required for the first control unit to output the first control signal.

5. when it is determined, as a result of the determination based on the abnormal signal, that neither the output of the first control signal for placing the upper arm in a conductive state and the lower arm in a non-conductive state nor the output of the first control signal for placing the lower arm in a conductive state and the upper arm in a non-conductive state should be performed, the first control unit does not output the first control signal, The power conversion device according to claim 3 , wherein the second control unit continues to output the second control signal by continuing the initial period.

6. when the first control unit determines, as a result of determination based on the abnormal signal, that neither the output of the first control signal for placing the upper arm in a conductive state and the lower arm in a non-conductive state nor the output of the first control signal for placing the lower arm in a conductive state and the upper arm in a non-conductive state should be performed, the first control unit outputs the second control signal instead of the first control signal; The power conversion device according to claim 4 , wherein the second control unit continues to output the second control signal by transmitting the output signal from the first control unit after the initial period ends.

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