JP2017017948A - Power conversion device and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable power conversion device and a vehicle.SOLUTION: The power conversion device includes a buck-boost control device 30 which, in activation processing, receives a notification that a relay 10 is in an ON state, and when there is no fault in sensors, switches a lower-stage switching element Sb to perform step-up control, and based on a voltage value detected by a DC link voltage detector 40, performs the abnormality determination of the lower-stage switching element Sb, and switches an upper-stage switching element Sa to perform step-down control, and based on a voltage value detected by the DC link voltage detector 40, performs the abnormality determination of the upper-stage switching element Sa.SELECTED DRAWING: Figure 3

Description

  Embodiments described herein relate generally to a power conversion device and a vehicle.

  The inverter includes a pair of switching elements connected in series between DC links (DC lines) that supply DC power. The switching elements connected in series in the inverter are electrically connected to the AC line. In a power converter including a function of boosting and stepping down the voltage of a DC power supply, a step-up / step-down function unit (converter) and an inverter share a DC link. The converter includes a pair of switching elements connected in series between the DC links. The switching elements connected in series in the converter are electrically connected to the high potential side terminal of the DC power supply.

  Conventionally, the presence / absence of an abnormality in the converter has been determined based on a decrease in the current output to the AC line during the operation of the inverter and the converter. Conventionally, a method for comparing the timing at which the gate control signal of the switching element is switched with the timing at which the voltage before and after switching is changed has been proposed.

JP 10-341578 A

  However, when the abnormality of the converter is determined in a state where the inverter and the converter are operated and the motor is driven, it is difficult to specify the failure location. For example, when a converter has a plurality of switching element pairs, when the inverter and the converter are operated, the plurality of switching element pairs operate in synchronization with each other, so that an abnormality of each switching element is determined. It was difficult.

  An object of the present invention is to provide a highly reliable power conversion device and vehicle that can identify a faulty part of a converter.

  The power conversion device according to the embodiment is connected in series between the battery voltage detector for detecting the voltage between the terminals connected to the DC power supply via the relay and the DC link, and connected to the DC link on the high potential side. A lower switching element connected to the upper switching element and the DC link on the low potential side, and a step-up / step-down control device for controlling the operation of the upper switching element and the lower switching element. A converter to which a voltage of a DC power supply is applied, a DC link voltage detector for detecting a voltage output from the converter, at least a pair of switching elements connected in series between the DC links, and controlling the operation of the switching elements AC line connected between the control device and the switching elements connected in series An inverter provided with a current detector for detecting a flowing current, wherein the step-up / step-down control device receives a notification that the relay is in an on state in the start-up process, and the battery voltage detector When no failure is detected based on the detection value from the DC link voltage detector and the current detector, the lower switching element is switched to perform boost control, and the DC link voltage detector detects the failure. The lower switching element is determined to be abnormal based on a voltage value, the upper switching element is switched to perform step-down control, and the upper switching element is determined to be abnormal based on the voltage value detected by the DC link voltage detector.

Drawing 1 is a figure showing roughly the example of composition of the power converter of an embodiment, and vehicles. FIG. 2 is a flowchart illustrating the operation of the power conversion device and the vehicle according to the embodiment. FIG. 3 is a flowchart for explaining the operation of the step-up / down function failure detection process of the flowchart shown in FIG. FIG. 4 is a diagram illustrating an example of a DC link voltage waveform in the step-up / down function failure detection process illustrated in FIG. 3. FIG. 5 is a diagram showing another example of the DC link voltage waveform in the step-up / down function failure detection process shown in FIG. 3. FIG. 6 is a diagram showing another example of the DC link voltage waveform in the step-up / down function failure detection process shown in FIG. 3.

Hereinafter, a power conversion device and a vehicle according to an embodiment will be described with reference to the drawings.
Drawing 1 is a figure showing roughly the example of composition of the power converter of an embodiment, and vehicles.
The vehicle of the present embodiment includes a battery BT, a relay 10, a power conversion device, a motor M, a magnetic pole position detector 70, wheels WL, and a vehicle ECU 100. The power converter includes a step-up / step-down function unit (converter) CON and a motor control function unit (inverter) INV.

The battery BT includes a storage battery such as a lithium ion battery or a nickel metal hydride battery. The DC power output from the battery BT is supplied to the power converter. The battery BT is a direct current load and can be charged with electric energy generated by the motor M connected via the power converter.
The relay 10 is an electromagnetic contactor, for example, and switches the connection between the battery BT and the power converter. The switching operation of relay 10 is controlled by vehicle ECU 100, and the rise of the voltage applied to converter CON by relay 10 can be blunted.

  The magnetic pole position detector 70 is, for example, a resolver, detects the angular position θ of the rotor of the motor M, and outputs it to the motor control device 50 and the step-up / down pressure control device 30. The magnetic pole position detector 70 may be a sensorless magnetic pole position estimator that estimates the magnetic pole position from the current information of the current detector 60 instead of a mechanical or magnetic sensor. In that case, the magnetic pole position detector 70 can be omitted.

  Converter CON steps up or down the voltage of battery BT. The converter CON includes switching elements Sa to Sf, inductances L1 to L3, a high voltage battery voltage detector 20, a capacitor C1, and a step-up / down control device 30. The converter CON shares the DC link voltage detector 40 with an inverter INV described later.

The high voltage battery voltage detector 20 detects a voltage applied between connection terminals to which the converter CON and the battery BT are connected. The voltage value detected by the high voltage battery voltage detector 20 is supplied to the step-up / step-down control device 30.
Capacitor C1 suppresses fluctuations in the voltage between connection terminals where converter CON and the battery are connected.

  The DC link voltage detector 40 detects a voltage between the high potential side DC link LINK (H) and the low potential side DC link LINK (L) between the converter CON and the inverter INV. The voltage value detected by the DC link voltage detector 40 is supplied to the step-up / step-down control device 30 and a motor control device 50 described later.

  The switching elements Sa to Sf are semiconductor switches such as FET (Field-Effect Transistor) and IGBT (Insulated Gate Bipolar Transistor). The switching elements Sa to Sf constitute three rows of switching element pairs connected in parallel. The switching elements Sa to Sf and a plurality of switching elements Su, Sx, Sv, Sy, Sw, and Sz of the inverter INV described later are connected in parallel with each other between the DC links.

  The switching element Sa and the switching element Sb in the first row are connected in series, the switching element (upper switching element) Sa is located on the upper stage (high potential side), and the switching element (lower switching) on the lower stage (low potential side). Element) It is connected between the DC links so that Sb is located. A connection portion between the switching element Sa and the switching element Sb is electrically connected to the positive terminal of the battery BT via the inductance L1. That is, the voltage of the battery BT is applied across the switching element Sb.

  The second row switching element Sc and the switching element Sd are connected in series with each other, and the DC link is such that the switching element (upper switching element) Sc is located in the upper stage and the switching element (lower switching element) Sd is located in the lower stage. Connected between. A connection portion between the switching element Sc and the switching element Sd is electrically connected to the positive terminal of the battery BT via the inductance L2. That is, the voltage of the battery BT is applied across the switching element Sd.

  The third row switching element Se and the switching element Sf are connected in series with each other, and the DC link is such that the switching element (upper switching element) Se is positioned in the upper stage and the switching element (lower switching element) Sf is positioned in the lower stage. Connected between. A connection portion between the switching element Se and the switching element Sf is electrically connected to the positive terminal of the battery BT via the inductance L3. That is, the voltage of the battery BT is applied across the switching element Sf.

  The step-up / down control device 30 includes, for example, a processor such as an MPU (micro processing unit) (not shown) and a memory, and is connected to the vehicle ECU 100 by communication means using a CAN protocol or the like. The step-up / step-down control device 30 detects the voltage value detected by the high voltage battery voltage detector 20, the voltage value detected by the DC link voltage detector 40, and the rotor of the motor M detected by the magnetic pole position detector 70. The angular position θ is received. Further, the step-up / step-down control device 30 receives an output command value from the vehicle ECU 100 which is a host control device. The step-up / step-down control device 30 generates a PWM signal so as to realize the received output command value using, for example, a carrier wave stored in a memory, and generates gate signals of the switching elements Sa to Sf based on the PWM signal. And output.

The inverter INV includes switching elements Su, Sx, Sv, Sy, Sw, Sz, a DC link voltage detector 40, a motor control device 50, a current detector 60, and a capacitor C2.
The inverter INV is connected between the converter CON and the AC load M, and includes a switch circuit including a pair of switching elements connected between the DC links LINK (H) and LINK (L) that supply DC power from the converter CON. At least one is provided. Each switch circuit includes two switching elements connected in series.

  In the present embodiment, the inverter INV is a three-phase inverter that converts DC power supplied from the converter CON into three-phase AC power. The inverter INV includes a plurality of switching elements Su, Sx, Sv, Sy, Sw, Sz, and the plurality of switching elements Su, Sx, Sv, Sy, Sw, Sz are provided according to a gate signal from a motor control device 50 described later. By opening and closing, a three-phase alternating current is supplied to the motor M. The U-phase switch circuit includes switching elements Su and Sx, the V-phase switch circuit includes switching elements Sv and Sy, and the W-phase switch circuit includes switching elements Sw and Sz. The switch circuits for each phase are connected in parallel with each other.

  In each phase switch circuit, switching elements are connected in series, and the switching elements are electrically connected to a motor M that is an AC load. For example, in the U-phase switch circuit, the pair of switching elements Su and Sx are connected in series, and the motor M is electrically connected between the pair of switching elements Su and Sx. The switching elements Su, Sx, Sv, Sy, Sw, Sz are, for example, IGBT (Insulated Gate Bipolar Transistor), FET (Field-Effect Transistor), GTO (gate turn-off thyristor), transistor, etc. It is a switching element that can be electrically opened and closed. In the power conversion device of the present embodiment, the switching elements Su, Sx, Sv, Sy, Sw, and Sz are IGBTs.

  The capacitor C2 is connected in parallel with the plurality of switching elements Su, Sx, Sv, Sy, Sw, and Sz between the converter CON and the inverter INV. Capacitor C2 suppresses fluctuations in the voltages of DC links LINK (H) and LINK (L) connected to inverter INV when converter CON and inverter INV are operated.

  The current detector 60 detects the current of each phase supplied from the inverter INV to the motor M that is an AC load. The current value of each phase detected by the current detector 60 is provided to the motor control device 50.

  The motor control device 50 includes, for example, a processor such as an MPU (micro processing unit) (not shown) and a memory, and is connected to the vehicle ECU 100 by communication means using a CAN protocol or the like. The motor control device 50 and the step-up / step-down control device 30 may share the MPU and the memory, and may have a plurality of MPUs and memories, respectively.

  The motor controller 50 detects the voltage value detected by the DC link voltage detector 40, each phase current value detected by the current detector 60, and the angle of the rotor of the motor M detected by the magnetic pole position detector 70. The position θ is received. Further, the motor control device 50 receives an output command value from the vehicle ECU 100 which is a host control device. The motor control device 50 generates a PWM signal so as to realize the received output command value using, for example, a carrier wave stored in a memory, and the switching elements Su, Sx, Sv, Sy, Sw based on the PWM signal , Sz gate signals are generated and output.

  As shown in FIG. 1, when two upper and lower switching elements are connected to each phase of the inverter INV, the motor control device 50 generates two gate signals for each phase. When generating two gate signals for each phase, the motor control device 50 can use, for example, a signal obtained by inverting the gate signal of the upper switching element as an open / close signal of the lower switching element. In general, it is desirable to provide a dead time period in which both the upper and lower switching elements are turned off in order to prevent the upper and lower switching elements of each phase of the inverter INV from being electrically short-circuited.

  The motor M is an AC load, and generates torque by the current supplied from the inverter INV. Torque generated by connecting a load device is transmitted to the output shaft of the motor M. The motor M performs regenerative operation by converting the kinetic energy of the load device into electric power. The electric power generated by the regenerative operation of the motor M is converted into DC power by the inverter INV and charged to the DC power source BT. In the present embodiment, the torque generated when the axle is connected to the output shaft of the motor M is transmitted to the wheel WL via the axle. Further, the motor M performs a regenerative operation by converting the kinetic energy of the wheels WL transmitted through the axle to electric power.

  FIG. 2 is a flowchart illustrating the operation of the power conversion device and the vehicle according to the embodiment.

In the power conversion device of this embodiment, the step-up / step-down control device 30 performs a step-up / step-down function failure detection process when the power conversion device is activated.
First, when the power converter is activated, the step-up / step-down control device 30 and the motor control device 50 detect whether or not the sensors are out of order. At this time, the step-up / step-down control device 30 and the motor control device 50 acquire values detected by the voltage detector and the current detector, and determine whether there is a short circuit or a disconnection. Here, the step-up / step-down control device 30 and the motor control device 50 notify the determination result to the vehicle ECU 100 that is the host control device. In the present embodiment, the power conversion device is activated even when a sensor failure occurs. The power conversion device performs a limited operation while detecting a failure of the sensors. During restricted operation, for example, when the upper / lower switching elements are fixed to the OFF state according to the location where the failure is detected, the upper switching element is fixed to ON, and the lower switching element is fixed to OFF. There are cases. (Step S1)

Subsequently, the vehicle ECU 100 turns on the relay 10. (Step S2)
Thereafter, the step-up / step-down control device 30 receives a notification from the vehicle ECU 100 that the relay 10 is turned on. (Step S3)

  Subsequently, the step-up / step-down control device 30 checks whether or not the conditions for performing the step-up / step-down function failure detection process are satisfied. The implementation condition of the step-up / down function failure detection process is that the converter CON has completed normal startup and has received a notification that the relay 10 is on. In the present embodiment, it is assumed that the normal startup of the inverter INV is completed because no failure of the sensors is detected in the motor control device 50. Similarly, it is assumed that normal startup of converter CON has been completed because no failure of the sensors has been detected in step-up / step-down control device 30. When the above condition is not satisfied, the step-up / step-down control device 30 in the next step does not perform the step-up / step-down function failure detection process. (Step S4)

  When it is confirmed that the above condition is satisfied, the step-up / step-down control device 30 performs a step-up / step-down function failure detection process. When the step-up / step-down function failure detection process ends and there is an abnormality in the step-up function or the step-down function (or both the step-up function and the step-down function), the step-up / step-down control device 30 notifies the vehicle ECU 100 of the abnormality. In the power conversion device of this embodiment, when there is an abnormality in the step-up / step-down function, the upper / lower switching elements are turned off and fixed to stand by and do not transition to the steady process. In addition, the power conversion device can continue the operation by limiting the function of the part where there is an abnormality. (Step S5)

Subsequently, the step-up / step-down control device 30 and the motor control device 50 perform steady processing of the power conversion device. At this time, the step-up / step-down control device 30 drives the switching element in the first row, the switching element in the second row, and the switching element in the third row of the converter CON in a state where they are synchronized with their phases shifted from each other. . (Step S6)
When the step-up / step-down control device 30 and the motor control device 50 receive a motor stop command from the vehicle ECU 100, the steady-state processing of the power conversion device is terminated. (Step S7)

FIG. 3 is a flowchart for explaining the operation of the step-up / down function failure detection process of the flowchart shown in FIG.
FIG. 4 is a diagram illustrating an example of a DC link voltage waveform in the step-up / down function failure detection process illustrated in FIG. 3. In the present embodiment, it is assumed that the voltage of the battery BT is 288V, the voltage after the boost control is 318V, and the voltage after the buck control is 288V. Further, during the step-up / step-down function failure detection process, the switching elements Su, Sx, Sv, Sy, Sw, and Sz of the inverter INV are in a non-conductive state.

  The step-up / step-down control device 30 sequentially operates the switching elements in the first column to the third column to determine whether or not the step-up control and the step-down control are normal.

  First, the step-up / step-down control device 30 repeats on / off of the lower switching element Sb with the upper switching element Sa turned off for the first row switching elements Sa, Sb, and performs step-up control for a certain period. Do. (Step S51)

  Subsequently, the step-up / step-down control device 30 receives the DC link voltage from the DC link voltage detector 40 after a certain period of time has elapsed. The step-up / step-down control device 30 compares the received DC link voltage with the step-up determination threshold value and determines whether or not the lower switching element Sb is operating normally. In this embodiment, the boost determination threshold is 308V. This boost determination threshold should be adjusted as appropriate according to the DC link voltage after boost control and the time required for the step-up / down function failure detection process. (Step S52)

The step-up / step-down control device 30 determines that there is an abnormality in the lower switching element Sb if the received DC link voltage is less than the boost determination threshold. (Step S53)
The step-up / step-down control device 30 determines that the lower switching element Sb is operating normally if the received DC link voltage is equal to or higher than the boost determination threshold. (Step S54)
Subsequently, the step-up / step-down control device 30 repeats step-down control of the first row switching elements Sa and Sb by repeatedly turning on and off the upper switching element Sa while the lower switching element Sb is turned off. I do. (Step S55)

  Subsequently, the step-up / step-down control device 30 receives the DC link voltage from the DC link voltage detector 40 after a certain period of time has elapsed. The step-up / step-down control device 30 compares the received DC link voltage with the step-down determination threshold value, and determines whether or not the upper switching element Sa is operating normally. In the present embodiment, the step-down determination threshold is 298V. This step-down determination threshold should be adjusted as appropriate according to the DC link voltage after step-down control and the time required for the step-up / down function failure detection process. (Step S56)

The step-up / step-down control device 30 determines that the upper switching element Sa is abnormal if the received DC link voltage is equal to or higher than the step-down determination threshold. (Step S57)
The step-up / step-down control device 30 determines that the upper switching element Sa is operating normally if the received DC link voltage is less than the boost determination threshold. (Step S58)
The step-up / step-down control device 30 performs the above-described steps S51 to S58 in the same manner for the second-phase switching elements Sc and Sd and the third-phase switching elements Se and Sf, and all the switching elements Sa to Sf fail. Judge whether there is. (Step S59)

FIG. 5 is a diagram showing another example of the DC link voltage waveform in the step-up / down function failure detection process shown in FIG. 3.
In this example, when the step-up / step-down function failure detection process described above performs the step-up control and the step-down control sequentially from the first phase, there is an abnormality in the step-down function of the third phase. That is, after the step-down control is normally performed for the second phase, the step-up control is performed by repeatedly turning on and off the lower-stage switching element Sf of the third phase for a certain period. When the link voltage was compared, the DC link voltage was less than the boost determination threshold. In this case, it is determined that the lower switching element Sf of the third phase is abnormal.

FIG. 6 is a diagram showing another example of the DC link voltage waveform in the step-up / down function failure detection process shown in FIG. 3.
In this example, when the step-up / step-down function failure detection process described above performs the step-up control and the step-down control sequentially from the first phase, there is an abnormality in the step-down function of the third phase. That is, after the step-up control is normally performed for the third phase, the step-down control is performed by repeatedly turning on and off the upper switching element Se of the third phase for a certain period. When the link voltage was compared, the DC link voltage was greater than or equal to the step-down determination threshold. In this case, it is determined that the upper switching element Se of the third phase is abnormal.

  As described above, in the step-up / down function failure detection process, converter CON operates differently from the normal operation of the power converter. In this embodiment, since the operation of the switching elements in the first column to the third column is sequentially confirmed in the step-up / step-down function failure detection process when the power conversion device is activated, it is possible to determine the abnormality of each switching element. That is, according to the present embodiment, it is possible to provide a highly reliable power conversion device and vehicle that can identify a faulty part of the converter.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, in the above-described embodiment, the converter CON includes a plurality of rows of switching element pairs. However, the step-up / down function failure detection process of the present embodiment is also applicable to a converter including one switching element pair. Even in that case, the same effect as the above-described embodiment can be obtained.

  DESCRIPTION OF SYMBOLS 10 ... Relay, 20 ... High voltage battery voltage detector, 30 ... Buck-boost control device, 40 ... DC link voltage detector, 50 ... Motor control device, 60 ... Current detector, 70 ... Magnetic pole position detector, C1, C2 ... Capacitor, 100 ... Vehicle ECU, L1-L3 ... Inductance, Sa-Sf ... Switching element, Su-Sz ... Switching element, CON ... Converter (step-up / step-down function unit), INV ... Inverter (motor control function unit), M ... AC Load (motor), BT ... DC load (battery), LINK (H), LINK (L) ... DC link.

Claims (3)

A battery voltage detector for detecting a voltage between terminals connected to a DC power source via a relay, and an upper switching element connected to the DC link on the high potential side and a low potential side connected to each other in series between the DC links A lower switching element connected to the DC link; and a step-up / step-down control device that controls operations of the upper switching element and the lower switching element, and a voltage of the DC power source is applied to both ends of the lower switching element. A converter,
DC link voltage detector for detecting the voltage output from the converter, at least a pair of switching elements connected in series between the DC links, a control device for controlling the operation of the switching elements, and switching elements connected in series A current detector for detecting a current flowing in an AC line connected between the inverter, and an inverter,
In the start-up process, the step-up / step-down control device receives a notification that the relay is on, and detects from the battery voltage detector, the DC link voltage detector, and the current detector. When no failure is detected based on the value,
The lower switching element is switched to perform step-up control, and the lower switching element is determined to be abnormal based on the voltage value detected by the DC link voltage detector.
The power conversion device, wherein the upper switching element is switched to perform step-down control, and abnormality of the upper switching element is determined based on a voltage value detected by the DC link voltage detector.   The power converter according to claim 1, wherein the converter includes a plurality of rows of the upper switching elements and the lower switching elements connected in series between the DC links. The power conversion device according to claim 1 or 2,
The DC power source as a DC load;
A motor as an AC load;
A host controller that switches between ON and OFF of the relay and notifies the step-up / step-down controller when the relay is turned ON;
An axle for transmitting the power of the motor to the wheels;
A vehicle characterized by comprising: