JP7201488B2 - Inverter protection device - Google Patents

Description

The present invention relates to an inverter protection device that converts power between a DC power supply and an AC rotating machine.

For example, in an electric vehicle such as an electric vehicle (EV) or a plug-in hybrid vehicle (PHEV), when a contactor is turned on, a secondary battery such as a lithium-ion battery is connected to a propulsion motor. On the propulsion motor side, the DC power of the secondary battery is smoothed by a smoothing capacitor. Further, when the inverter operates, the smoothed DC power is converted to AC power by the inverter. The AC power supplied from the inverter rotates a propulsion motor, which is an AC rotating machine.

It is said that the line-to-line voltage of the propulsion motor is, for example, about 800 V when the electric vehicle is running at 100 km/h. Some electric vehicles reach a maximum speed of 140 km/h, and the line voltage of the propulsion motor at that time is considered to exceed 1000V.

By the way, if the contactor is turned off due to an abnormality while the propulsion motor is rotating, an induced voltage corresponding to the rotational speed is generated in the propulsion motor. In addition, current stops flowing through the coils of the propulsion motor, and stored energy corresponding to the current flowing through the coils is released from the coils. A similar situation occurs in the propulsion motor when the operation of the inverter is abnormally stopped while the propulsion motor is rotating.

For example, when an electric vehicle is running at maximum speed, if an abnormality causes the contactor to turn off or the inverter to stop operating, an induced voltage is generated and the energy stored in the coil is released. High voltages in excess of 1000V can appear.

When the contactor is turned off or the inverter stops operating due to an abnormality, the high voltage appearing between the lines of the propulsion motor greatly exceeds the terminal voltage of the secondary battery. When such an abnormally high voltage occurs between the lines of the propulsion motor, the abnormally high voltage is applied to the power semiconductor switching elements and smoothing capacitors of the inverter on the regenerative current path. Then, the power semiconductor switching element or the smoothing capacitor may be damaged by the application of overvoltage exceeding the withstand voltage. Therefore, measures have been proposed in the past to deal with the case where the contactor is turned off while the propulsion motor is rotating.

In this proposal, the electrical energy of the voltage generated between the lines of the propulsion motor when the contactor is turned off is accumulated in a smoothing capacitor, so that the sudden increase of the line voltage of the propulsion motor is unlikely to occur. In addition, when the contactor is detected to be turned off while the propulsion motor is rotating, the semiconductor switching element of the inverter is controlled to open and close, and the line voltage of the propulsion motor is lowered by the switching loss of the semiconductor switching element. Patent document 1).

JP 2017-225236 A

In the above-mentioned countermeasure for opening and closing the semiconductor switching elements of the inverter by control, overcurrent may flow through the semiconductor switching elements that are turned on by the control due to the induced voltage generated in the propulsion motor and the energy stored in the coil. have a nature. Passage of such an overcurrent can cause damage to semiconductor switching elements. If the semiconductor switching element is damaged, it becomes impossible to open and close the semiconductor switching element by control and lower the line voltage of the propulsion motor due to the switching loss of the semiconductor switching element.

Therefore, it is conceivable to increase the storage amount of electric energy by increasing the capacity of the smoothing capacitor. However, it is difficult to say that this is an ideal countermeasure because it is inevitable that the size and cost of the smoothing capacitor will increase.

The present invention has been made in view of the above circumstances, and an object of the present invention is to appropriately protect an inverter from abnormal electrical energy generated by abnormal operation during rotation of a rotating machine such as a motor for propulsion of an electric vehicle. It's about making it possible.

In order to achieve the above object, an inverter protection device according to one aspect of the present invention includes:
a DCDC converter whose output side is connected in parallel with the high voltage battery to the input side of an inverter that converts the DC power of the high voltage battery into AC power and supplies it to the rotating machine;
a DC link capacitor connected to the input side of the DCDC converter;
a sensor that detects a voltage between inputs of the inverter;
an electric circuit that controls the operation of the DCDC converter to connect the input side of the inverter and the DC link capacitor when the detected voltage of the sensor is equal to or higher than the judgment value of the overvoltage state of the inverter; a controller formed on the DCDC converter;
Prepare.

Advantageous Effects of Invention According to the present invention, it is possible to appropriately protect an inverter from abnormal electrical energy generated due to an operational abnormality during rotation of a rotating machine.

1 is a block diagram showing a power control unit of an electric vehicle to which an inverter protection device according to an embodiment of the invention is applied; FIG. 2 is a circuit diagram schematically showing a circuit configuration of a power supply path from the high voltage battery of FIG. 1 to a propulsion motor; FIG. Schematic configuration of a circuit that absorbs electrical energy generated in the propulsion motor due to an abnormality during rotation, with the main part of the plug-in charger added to the power supply path from the high-voltage battery to the propulsion motor shown in FIG. is a circuit diagram shown in FIG. 4 is a flow chart showing an example of a control procedure executed by the controller of FIG. 1 according to a program in order to absorb electrical energy generated in the propulsion motor due to an abnormality during rotation by the circuit of FIG. 3. FIG. 2 is a timing chart showing voltages or signal states of each part of the plug-in charger when the main relay is turned off or the power module is stopped due to an abnormality during rotation of the propulsion motor shown in FIG. 1;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a power control unit of an electric vehicle to which an inverter protection device according to one embodiment of the invention is applied. A power control unit 1 of the present embodiment shown in FIG. 1 is mounted on an electric vehicle such as an electric vehicle (EV) or a plug-in hybrid vehicle (PHEV).

The power control unit 1 of this embodiment is a combination of elements related to charging and discharging of the high voltage battery HB mounted on the electric vehicle and elements related to charging of the low voltage battery LB also mounted on the electric vehicle.

The power control unit 1 has a high-voltage battery port HBP, a low-voltage battery port LBP, a signal port SP, a power port PP, a quick charge port QP, and a commercial power port CP as connection ports for external devices. .

A high voltage battery HB is connected to the high voltage battery port HBP via a main relay (M/R) 3 (corresponding to a contactor in claims). Therefore, the high-voltage battery port HBP and the high-voltage battery HB are connected and disconnected by turning the main relay 3 on and off. When the main relay 3 is turned on, the high voltage battery HB supplies high voltage power (for example, DC 400 V) to the high voltage battery port HBP. The high-voltage power supplied by the high-voltage battery HB is used to drive a propulsion motor M (corresponding to a rotating machine in the claims) of the electric vehicle.

The high-voltage battery HB has a sensor (not shown) for measuring terminal voltage. The terminal voltage of the high-voltage battery HB measured by the sensor is input to a vehicle integrated controller (VCM) 5 of the electric vehicle, which will be described later.

A low voltage battery LB is connected to the low voltage battery port LBP. The low-voltage battery LB supplies low-voltage power (for example, DC 12 V) for operation to auxiliary equipment (electrical equipment such as on-vehicle instruments and lamps) ACC of the electric vehicle.

The accessory ACC of the electric vehicle includes the vehicle integrated controller 5 described above and a controller 27 (corresponding to the controller in the claims) of the power control unit 1 described later. Therefore, the vehicle integrated controller 5 and the controller 27 operate with the low-voltage DC power supplied from the low-voltage battery LB.

The vehicle integrated controller 5 can be composed of, for example, one of a plurality of ECUs (Electronic Control Units or Engine Control Units) mounted on the electric vehicle. For this reason, the vehicle integrated controller 5 uses, for example, the LAN of the electric vehicle used for communication between ECUs to transmit the high-voltage battery HB sensor-measured high-voltage battery HB sensor from another ECU to which the high-voltage battery HB sensor is connected. Terminal voltage can be obtained.

Then, the vehicle integrated controller 5 detects the state of charge (for example, SOC: State of Charge) of the high voltage battery HB based on the acquired terminal voltage of the high voltage battery HB. Furthermore, the vehicle integrated controller 5 can control on/off of the main relay 3 during rapid charging according to the detected state of charge of the high voltage battery HB.

The vehicle integrated controller 5 also acquires the accelerator operation amount of the electric vehicle detected by a sensor (not shown). For example, the vehicle integrated controller 5 can acquire the accelerator operation amount via the LAN of the electric vehicle from another ECU to which a sensor (not shown) that detects the accelerator operation amount is connected. Then, the vehicle integrated controller 5 can determine a torque command value for the propulsion motor M according to the acquired accelerator operation amount.

A vehicle integrated controller 5 is connected to the signal port SP. The vehicle integrated controller 5 outputs the determined torque command value to the signal port SP.

An external power output port (not shown) of the vehicle integrated controller 5 is connected to the power port PP. The vehicle integrated controller 5 outputs to the power supply port PP a power supply voltage VCC generated from low voltage power (for example, DC 12 V) supplied from the low voltage battery LB.

A connector 9 of a charging cable 7 of a quick charger QC is connected to the quick charge port QP. When the charging cable 7 is connected to the quick charging port QP, DC power (for example, maximum DC 600V) for quick charging of the high voltage battery HB is supplied from the quick charger QC to the quick charging port QP via the charging cable 7. be.

Also, when the charging cable 7 is connected to the quick charge port QP, the communication line of the quick charger QC is connected to the LAN inside the power control unit 1 . The controller 27 is connected to this LAN as described above. Therefore, when charging cable 7 is connected to quick charge port QP, quick charger QC and controller 27 are communicably connected.

A connector 13 of a charging cable 11 for normal charging is connected to the commercial power supply port CP. Charging cable 11 has a plug 15 on the opposite side of connector 13 . The plug 15 of the charging cable 11 is connected to a normal charging outlet (not shown) of a commercial power source. When the charging cable 11 connected to the commercial power supply is connected to the commercial power supply port CP, AC power of the commercial power supply (for example, single-phase AC 200V) is supplied to the commercial power supply port CP via the charging cable 11 .

Also, the charging cable 11 has a control box 17 . A communication line of the charging cable 11 is connected to the control box 17 . When the charging cable 11 is connected to the commercial power supply port CP, the communication line of the charging cable 11 is connected to the LAN inside the power control unit 1 . Therefore, when the charging cable 11 is connected to the commercial power supply port CP, the controller 27 is communicably connected to the control box 17 .

The power control unit 1 to which the above-described external devices are connected includes a junction box (J/B) 19, a plug-in charger CHG, a DCDC converter 21, an inverter unit 23, a discharge circuit 25, and the controller 27 described above. have.

Junction box 19 has a QC relay (not shown). The QC relay turns on and off the connection between the quick charge port QP and the high voltage battery port HBP. The ON/OFF of the QC relay permits or prohibits the output of the DC power for quick charging input from the quick charging port QP to the high voltage battery HB from the high voltage battery port HBP.

Plug-in charger CHG operates with power supply voltage VCC supplied from controller 27 . The plug-in charger CHG converts AC power from a commercial power supply input from the commercial power supply port CP into DC power (for example, maximum DC 400 V) for normal charging of the high voltage battery HB. Then, the converted DC power is output from the high voltage battery port HBP to the high voltage battery HB through the power path 28 connecting the junction box 19 and the high voltage battery port HBP.

The plug-in charger CHG includes, for example, a rectifier circuit (not shown) that converts AC power from a commercial power source into DC power, and a DCDC converter 39 (see FIG. 3, DCDC in claims) that boosts the rectified DC power. (equivalent to a converter) can be used. The rectifier circuit can be composed of, for example, a diode bridge circuit. Also, the DCDC converter 39 can be composed of, for example, an insulated DCDC converter having an insulating transformer and a power semiconductor switching element.

Further, the plug-in charger CHG has a voltage sensor 45 (see FIG. 3, corresponding to the sensor in the claims) which will be described later. This voltage sensor 45 measures the DC voltage on the power path 28 between the junction box 19 and the high voltage battery port HBP.

Here, when the electric vehicle is running, the QC relay of the junction box 19 is turned off and the quick charge port QP is cut off from the power path 28 . Further, when the electric vehicle is running, the main relay 3 is turned on to connect the high voltage battery HB to the high voltage battery port HBP. Furthermore, when the electric vehicle is running, the DC power converted from the AC power of the commercial power source by the plug-in charger CHG is not supplied to the power path 28 .

Therefore, when the electric vehicle is running, the DC voltage on the power path 28 measured by the voltage sensor 45 of the plug-in charger CHG is the terminal voltage of the high voltage battery HB.

The measured value of voltage sensor 45 of plug-in charger CHG is input to controller 27 . Note that the plug-in charger CHG and the controller 27 are connected via a LAN within the power control unit 1, as will be described later.

For example, an IGBT (Insulated Gate Bipolar Transistor) can be used as the power semiconductor switching element of the plug-in charger CHG. Further, the plug-in charger CHG can be provided with a DC link capacitor (not shown) in the preceding stage of the rectifier circuit (commercial power port CP side).

The DCDC converter 21 converts part of the high-voltage DC power on the power path 28 connecting the junction box 19 and the high-voltage battery port HBP into DC power (for example, DC 12V) for charging the low-voltage battery LB. do.

That is, the DCDC converter 21 converts part of the DC power of the high-voltage battery HB input from the high-voltage battery port HBP into DC power for charging the low-voltage battery LB, and converts a portion of the DC power to the low-voltage battery port LBP into low-voltage Output to battery LB. Further, the DCDC converter 21 converts part of the DC power for normal charging of the high-voltage battery HB output by the plug-in charger CHG into DC power for charging the low-voltage battery LB, and converts it into DC power for charging the low-voltage battery port. Output from LBP to low voltage battery LB.

For the DCDC converter 21, for example, an asymmetrical half-bridge LLC converter can be used. An asymmetric half-bridge LLC converter has an LLC circuit on the primary side of an isolation transformer and a rectifier circuit on the secondary side.

In this asymmetrical half-bridge LLC converter, part of the DC power from the high-voltage battery HB or the plug-in charger CHG is converted to AC by the ON/OFF operation of the power semiconductor switching elements in the LLC circuit on the primary side. Then, the AC power stepped down according to the turns ratio between the primary coil and the secondary coil in the transformer is converted into DC power for charging the low-voltage battery LB in the rectifier circuit.

For example, an IGBT can be used for the power semiconductor switching element of the DCDC converter 21 as well as the plug-in charger CHG.

The inverter unit 23 is connected to a power path 28 connecting the junction box 19 and the high voltage battery port HBP. The inverter unit 23 operates with the power supply voltage VCC supplied from the vehicle integrated controller 5 through the power supply port PP.

The inverter unit 23 has a smoothing capacitor 29 , a power module (PM) 31 , a motor controller (MC) 33 and a drive circuit (DR) 35 .

The smoothing capacitor 29 smoothes the high-voltage DC power current flowing through the power path 28 connecting the junction box 19 and the high-voltage battery port HBP.

That is, switching noise is superimposed on the high-voltage DC power flowing through the power path 28 connecting the junction box 19 and the high-voltage battery port HBP. This switching noise is generated by the ON/OFF operation of the power semiconductor switching element of the plug-in charger CHG or the DCDC converter 21 . The smoothing capacitor 29 smoothes the high-voltage DC power current on which the switching noise of the power semiconductor switching element is superimposed. The smoothing capacitor 29 outputs the smoothed high-voltage DC power to the power module 31 , excluding the part supplied to the DCDC converter 21 , by dividing it into each phase of UVW.

The power module 31 is a three-phase alternating current inverter circuit having power semiconductor switching elements (not shown) in upper and lower arms of each UVW phase. In the power module 31, the DC power of the high-voltage battery HB smoothed by the smoothing capacitor 29 is converted into three-phase AC power by the ON/OFF operation of each power semiconductor switching element. For example, an IGBT can be used as the power semiconductor switching element. The converted three-phase AC power is supplied to the UVW phase coils of the propulsion motor M, respectively.

The motor controller 33 is connected to the signal port SP and the controller 27 via the LAN inside the power control unit 1 . A torque command value from the vehicle integrated controller 5 connected to the signal port SP is input to the motor controller 33 . The motor controller 33 outputs a pulse signal having a duty ratio corresponding to the input torque command value to the drive circuit 35 .

The drive circuit 35 generates a control signal based on the pulse signal input from the motor controller 33 and outputs the control signal to the control electrode (for example, IGBT gate) of each power semiconductor switching element of the power module 31 . This control signal causes the drive circuit 35 to turn on/off each power semiconductor switching element of the power module 31 .

Control signals input from the drive circuit 35 to the control terminals cause the power semiconductor switching elements of the power module 31 to turn on and off in a pattern that causes the propulsion motor M to output torque corresponding to the torque command value from the vehicle integrated controller 5. do.

Note that the inverter unit 23 may convert DC power into multiphase AC power of three or more phases (description of the configuration of the inverter in that case is omitted).

The discharge circuit 25 is a circuit for discharging the residual electric charge of the smoothing capacitor 29, and can be configured to include, for example, a series circuit of a discharge resistor 37 and a discharge switch (not shown). This series circuit is provided between inverter unit 23 and junction box 19 on power path 28 connecting junction box 19 and high voltage battery port HBP.

A series circuit of the discharge resistor 37 and the discharge switch is connected across a positive (P pole) line 28P and a negative (N pole) line 28N of the power path 28 . A discharge switch (not shown) is normally turned off (opened). When the residual charge of the smoothing capacitor 29 is discharged by the discharge circuit 25 , a discharge switch (not shown) is turned on (closed) under the control of the controller 27 .

The controller 27 operates on low-voltage DC power supplied from the low-voltage battery LB through the low-voltage battery port LBP. The controller 27 is connected to the signal port SP and the motor controller 33 of the inverter unit 23 as well as to the DCDC converter 21 and the plug-in charger CHG via the LAN within the power control unit 1 .

The controller 27 turns on the QC relay of the junction box 19 when the charging cable 7 of the quick charger QC is connected to the quick charge port QP and communication with the quick charger QC is established. As a result, the quick charge port QP and the high voltage battery port HBP are connected via the power path 28, and the high voltage battery HB can be rapidly charged.

When the controller 27 receives a connection confirmation signal from the control box 17 of the charging cable 11 when the charging cable 11 for normal charging connected to the commercial power supply is connected to the commercial power supply port CP, the controller 27 performs QC of the junction box 19 . turn off the relay. As a result, the quick charge port QP is disconnected from the power path 28, and the plug-in charger CHG and the high voltage battery port HBP are connected via the power path 28, enabling normal charging of the high voltage battery HB. state.

It should be noted that even in a state in which either rapid charging or normal charging of the high-voltage battery HB is possible, the low-voltage battery LB is charged with the low-voltage DC power converted by the DCDC converter 21 in parallel with the charging of the high-voltage battery HB. becomes possible.

Further, when the electric vehicle runs in which the propulsion motor M is driven by the high voltage DC power of the high voltage battery HB converted into three-phase AC power by the inverter unit 23, the controller 27 operates the QC relay of the junction box 19. turn it off. Then, the controller 27 starts driving the inverter unit 23 and the like.

Further, the controller 27 acquires the measured value by the voltage sensor of the plug-in charger CHG when the QC relay of the junction box 19 is off, such as when the electric vehicle is running, as the terminal voltage of the high-voltage battery HB. do. Then, the controller 27 can determine the target value of the charging current during normal charging according to the obtained terminal voltage of the high-voltage battery HB, and notify the plug-in charger CHG of the target value.

The controller 27 also monitors the voltage across the terminals of the smoothing capacitor 29 of the inverter unit 23 (the voltage across the DC input of the inverter) based on the acquired terminal voltage of the high-voltage battery HB. Then, the operation of the plug-in charger CHG is controlled according to the monitored level of the voltage between the DC inputs. Further, the controller 27 controls the discharge operation of the accumulated electric charge of the smoothing capacitor 29 by turning on/off a discharge switch (not shown) of the discharge circuit 25 .

Further, when the controller 27 detects connection of the charging cables 7, 11 for quick charging or normal charging to the quick charging port QP or the commercial power supply port CP, the controller 27 notifies the vehicle integrated controller 5 connected to the signal port SP to that effect. can be notified to

Note that the LAN in the power control unit 1 can be configured by an in-vehicle network using a communication protocol such as CAN (Controller Area Network).

In the power control unit 1 of this embodiment configured as described above, when the main relay 3 is turned on by the vehicle integrated controller 5, the high-voltage DC power of the high-voltage battery HB is transmitted through the main relay 3. Input to battery port HBP. A portion of the high-voltage DC power input to the high-voltage battery port HBP is supplied to the DCDC converter 21 and the rest is all supplied to the inverter unit 23 .

The high-voltage DC power supplied to the DCDC converter 21 is converted into low-voltage DC power and output to the low-voltage battery port LBP as charging power for the low-voltage battery LB. The high-voltage DC power supplied to the inverter unit 23 is converted into three-phase AC power by the inverter unit 23 and supplied to the UVW phase coils of the propulsion motor M, respectively. The propulsion motor M to which the three-phase AC power is supplied is rotated at a speed corresponding to the torque command value determined by the vehicle integrated controller 5 according to the operation amount of the accelerator.

In the power control unit 1 , when the controller 27 detects connection of the charging cable 7 for quick charging to the quick charging port QP while the electric vehicle is parked, the controller 27 turns on the QC relay of the junction box 19 . Also, the main relay 3 is turned on by the vehicle integrated controller 5 notified from the controller 27 .

When the QC relay is turned on, high voltage DC power from the quick charger QC is input to the quick charge port QP. A portion of the high voltage DC power input to the quick charge port QP is supplied to the DCDC converter 21, and the rest is all supplied to the high voltage battery port HBP.

The high-voltage DC power supplied to the DCDC converter 21 is converted into low-voltage DC power and output to the low-voltage battery port LBP as charging power for the low-voltage battery LB. The high-voltage DC power supplied to the high-voltage battery port HBP is output to the high-voltage battery HB via the main relay 3 as power for rapid charging of the high-voltage battery HB.

Further, in the power control unit 1, when the controller 27 detects connection of the charging cable 11 for normal charging connected to the commercial power supply to the commercial power supply port CP while the electric vehicle is parked, the AC power of the commercial power supply is switched to the commercial power supply. Input to port CP. The AC power of the commercial power supply input to the commercial power supply port CP is converted into high-voltage DC power by the plug-in charger CHG. The converted high voltage DC power is supplied to the high voltage battery port HBP. The high-voltage DC power supplied to the high-voltage battery port HBP is output to the high-voltage battery HB via the main relay 3 as power for normal charging of the high-voltage battery HB.

In the power control unit 1 of this embodiment described above, the DC power of the high-voltage battery HB is converted into AC power by the smoothing capacitor 29 and the power module 31 of the inverter unit 23 and supplied to the propulsion motor M. FIG. 2 is a circuit diagram schematically showing the circuit configuration of the power supply path from the high voltage battery HB to the propulsion motor M. As shown in FIG.

As shown in FIG. 2, the power module 31 of the inverter unit 23 has upper arm and lower arm power semiconductor switching elements corresponding to each phase coil (not shown) of the propulsion motor M. As shown in FIG. The power module 31 of this embodiment uses IGBTs (Insulated Gate Bipolar Transistors) Q1 to Q6 as power semiconductor switching elements.

The IGBTs Q1 to Q3 of the upper arm and the IGBTs Q4 to Q6 of the lower arm of each phase are connected between the positive (P pole) line 31P and the negative (N pole) line 31N to output lines 31U, 31V and 31V to the propulsion motor M. 31W are connected in series. The positive (P pole) line 31P and the negative (N pole) line 31N are connected to the main relay 3, the positive (P pole) line 28P and the negative (N pole) line 28N of the electric power path 28, and the smoothing capacitor 29. High voltage DC power is supplied from a voltage battery HB.

In the block diagram of FIG. 1, the positive (P-pole) line 31P and the negative (N-pole) line 31N of the power module 31 connected to the smoothing capacitor 29 are shown separately for three phases of UVW. However, in the circuit diagram of FIG. 2, the positive (P pole) line 31P and the negative (N pole) line 31N of each phase of UVW are schematically indicated by one line.

The propulsion motor M is rotated by AC power supplied from the power module 31 of the inverter unit 23 to the UVW phase coils. The electric vehicle travels as the propulsion motor M rotates.

For example, when the main relay 3 is turned off due to an abnormality such as vibration during the rotation of the propulsion motor M, an induced voltage corresponding to the rotational speed of the propulsion motor M is generated in the propulsion motor M. Further, when the main relay 3 is turned off while the propulsion motor M is rotating, the electric current does not flow through the coils of the respective phases of the propulsion motor M, and the stored energy corresponding to the current flowing through the coils of the respective phases is released into the coils. emitted from A similar situation occurs in the propulsion motor M when the operation of the power module 31 of the inverter unit 23 is abnormally stopped while the propulsion motor M is rotating.

For example, if the main relay 3 is turned off or the operation of the power module 31 is stopped due to an abnormality while the electric vehicle is running at the maximum speed, the voltage appearing between the lines of the propulsion motor M will be the voltage of the high voltage battery HB. It may rise to 1000V, which greatly exceeds the terminal voltage.

When the main relay 3 is turned off or the operation of the power module 31 is stopped due to an abnormality, the high voltage appearing between the lines of the propulsion motor M is applied to the IGBTs Q1 to Q6 of the power module 31 and the smoothing capacitor 29 existing on the regenerative current path. be. Then, the IGBTs Q1 to Q6 or the smoothing capacitor 29 may be damaged by the application of overvoltage exceeding the withstand voltage. On the other hand, increasing the capacitance of the smoothing capacitor 29 in order to increase the withstand voltage is not realistic because it causes an increase in the size and cost of the smoothing capacitor 29 .

Therefore, in the power control unit 1 of the present embodiment, the DC link capacitor C2, which will be described later, of the plug-in charger CHG, which is not operating while the propulsion motor M is rotating, is used to prevent the propulsion motor M from rotating in the event of an abnormality during rotation. The electric energy generated in the motor M is absorbed.

Hereinafter, referring to the schematic circuit diagram of FIG. 3, which is a circuit of the main part of the plug-in charger CHG added to the circuit of FIG. The configuration for

As shown in FIG. 3, the plug-in charger CHG has a DCDC converter 39 for boosting DC power. The DCDC converter 39 has a transformer L, and a primary side full bridge circuit BR1 and a secondary side full bridge circuit BR2 connected to the primary side and secondary side of the transformer L, respectively.

The primary side full bridge circuit BR1 has two half bridges. One half bridge is composed of a series circuit of high-side and low-side MOSFETs Q11 and Q12. The other half bridge is composed of a series circuit of high-side and low-side MOSFETs Q13 and Q14.

The secondary side full bridge circuit BR2 also has two half bridges like the primary side full bridge circuit BR1. One half bridge is composed of a series circuit of high-side and low-side MOSFETs Q15 and Q16. The other half bridge consists of a series circuit of high-side and low-side MOSFETs Q17 and Q18.

In this embodiment, n-channel MOSFETs are used for the MOSFETs Q11 to Q18 of the primary side full bridge circuit BR1 and the secondary side full bridge circuit BR2. Each of the MOSFETs Q11-Q18 is turned on and off by a gate drive circuit (not shown). This gate drive circuit is driven by a gate drive signal output by the controller 27 in FIG. The MOSFETs Q11 to Q18 used in the primary side full bridge circuit BR1 and the secondary side full bridge circuit BR2 of the DCDC converter 39 correspond to semiconductor switching elements in claims.

The plug-in charger CHG further has a DC link capacitor C2 on the primary side of the transformer L and a rectifier circuit (not shown). Further, the plug-in charger CHG further has a high frequency filter 41 and a contactor 43 on the secondary side of the transformer L. As shown in FIG. Furthermore, the plug-in charger CHG has a voltage sensor 45 .

The DC link capacitor C2 is connected to the half bridge (series circuit of MOSFETs Q11 and Q12) on the input side of the primary side full bridge circuit BR1. A rectifying circuit (not shown) is connected to the input side of the DC link capacitor C2. The rectifier circuit rectifies AC power of a commercial power source into DC power, and can be configured by a diode bridge circuit, for example.

The high frequency filter 41 is connected to a half bridge (a series circuit of MOSFETs Q17 and Q18) on the output side of the secondary side full bridge circuit BR2. The high-frequency filter 41 can be configured by, for example, a T-type filter circuit including a coil L3 and a capacitor C3. The contactor 43 is connected to the output side of the high frequency filter 41 . The contactor 43 connects and disconnects the high frequency filter 41 (the output side of the secondary side full bridge circuit BR2) and the input side of the power module 31 of the inverter unit 23 . In this embodiment, it is assumed that the contactor 43 is always turned on for the reason described later.

Note that in the block diagram of FIG. 1 , the output side of the plug-in charger CHG is connected to the power path 28 between the main relay 3 and the smoothing capacitor 29 of the inverter unit 23 . However, in the circuit diagram of FIG. 3 , the output side of the plug-in charger CHG is connected between the smoothing capacitor 29 of the inverter unit 23 and the power module 31 . By connecting the output side of the plug-in charger CHG between the smoothing capacitor 29 and the power module 31, the smoothing capacitor 29 can be more protected from the electric energy generated in the propulsion motor M due to an abnormality during rotation. can be certain.

The voltage sensor 45 is connected between the smoothing capacitor 29 connected to the output side of the plug-in charger CHG and the power module 31, and between the positive (P pole) line 31P and the negative (N pole) line 31N of the power module 31. Measure the DC voltage. That is, the voltage sensor 45 measures the voltage between the inputs of the inverter unit 23 .

While the propulsion motor M is rotating, the quick charge port QP is cut off from the power path 28, and the DC power converted from the AC power of the commercial power supply by the plug-in charger CHG is not supplied to the power path 28. A high voltage battery HB is connected to the high voltage battery port HBP.

Therefore, the input voltage of the inverter unit 23 measured by the voltage sensor 45 during the rotation of the propulsion motor M is the same as that of the high voltage battery if there is no abnormality in the operation of the main relay 3 and the IGBTs Q1 to Q6 of the power module 31. HB terminal voltage.

On the other hand, the input voltage of the inverter unit 23 measured by the voltage sensor 45 during the rotation of the propulsion motor M changes to The generated abnormally high voltage. This abnormally high voltage reaches, for example, 1000V, which greatly exceeds the terminal voltage of the high voltage battery HB, depending on the rotational speed of the propulsion motor M.

Therefore, it is possible to determine whether or not the main relay 3 is turned off or the operation of the power module 31 is stopped due to an abnormality by using the voltage between the inputs of the inverter unit 23 measured by the voltage sensor 45 while the propulsion motor M is rotating. can.

Next, an example of a control procedure executed by the controller 27 of FIG. 1 according to a program in order to absorb the electrical energy generated in the propulsion motor M due to an abnormality during rotation will be described with reference to the flowchart of FIG. do. The controller 27 periodically and repeatedly executes the procedure shown in the flowchart of FIG.

First, the controller 27 confirms whether or not the input voltage (DC input voltage) of the inverter unit 23 measured by the voltage sensor 45 during rotation of the propulsion motor M has increased to the first determination value ref1 ( step S1). The first judgment value ref1 is a reference value for judging whether the main relay 3 is turned off or the operation of the power module 31 is stopped due to an abnormality, based on the voltage between the DC inputs measured by the voltage sensor 45 while the propulsion motor M is rotating. is.

If the DC input voltage has not risen to the first judgment value ref1 (NO in step S1), the process proceeds to step S9, which will be described later. On the other hand, when the DC input voltage rises to the first judgment value ref1 (YES in step S1), the controller 27 drives the MOSFETs Q15 to Q18 of the secondary side full bridge circuit BR2 of the DCDC converter 39 (step S3 ).

At this time, the controller 27 alternately controls the high-side and low-side MOSFETs Q15, Q16, Q17, and Q18 in each half bridge of the secondary side full bridge circuit BR2 with a dead time for preventing the generation of through current interposed therebetween. turn off.

The cycle in which the MOSFETs Q15 and Q16 of one half bridge are alternately turned on and off is shifted by half a cycle from the cycle in which the MOSFETs Q17 and Q18 of the other half bridge are alternately turned on and off. Therefore, the MOSFETs Q16 and Q17 are turned off during the turn-on period of the MOSFETs Q15 and Q18, and the MOSFETs Q15 and Q18 are turned off during the turn-on period of the MOSFETs Q16 and Q17.

FIG. 5 shows the voltage or signal state of each part of the plug-in charger CHG when the main relay 3 is turned off or the operation of the power module 31 is stopped due to an abnormality while the propulsion motor M is rotating. Description will be made with reference to the timing chart. FIG. 5 shows an example in which the main relay 3 is switched from ON to OFF due to an abnormality while the propulsion motor M is rotating.

The timing chart of FIG. 5(a) shows the voltage level of the high voltage battery port HBP of FIG. In the example of FIG. 5, the voltage level of the high voltage battery port HBP is ON level when the main relay 3 is ON, and the voltage level of the high voltage battery port HBP is OFF level when the main relay 3 is OFF.

When the main relay 3 is turned off while the propulsion motor M is rotating, the DC input voltage measured by the voltage sensor 45 while the propulsion motor M is rotating becomes high, as shown in the timing chart of FIG. The voltage at the terminals of the voltage battery HB begins to rise. Then, when the voltage between the DC inputs rises to the first judgment value ref1 (overvoltage threshold), the judgment result of the main relay 3 or the power module 31 by the controller 27 is shown in the timing chart of FIG. 5(c). so that it switches from normal to abnormal.

At this time, as shown in the timing chart of FIG. 5(d), the contactor 43 continues to be on before and after the determination result of the controller 27 is switched from normal to abnormal. Then, when the determination result of the controller 27 switches from normal to abnormal, the controller 27, as shown in the timing chart of FIG. output the gate drive signal.

The gate drive signal in FIG. 5(e) is an AC signal with a duty ratio of 50% in which +side pulses and -side pulses of the same time and magnitude are alternately generated. When the electric energy generated in the propulsion motor M due to an abnormality during rotation is absorbed by the DC link capacitor C2, if the voltage across the terminals of the DC link capacitor C2 is low, the DC link capacitor C2 An inrush current will flow. Therefore, the duty ratio of the gate drive signal in FIG. 5(e) may be gradually brought closer to 50% from a value lower than 50%.

The plus side pulse of the gate drive signal is a signal component that turns on the MOSFETs Q15 and Q18 and turns off the MOSFETs Q16 and Q17. The minus side pulse of the gate drive signal is a signal component that turns on the MOSFETs Q16 and Q17 and turns off the MOSFETs Q15 and Q18.

Between the + side pulse and the - side pulse of the gate drive signal, there is provided a dead time component of a short period compared to both pulses. The dead-time component prevents both high-side and low-side MOSFETs Q15, Q16, Q17, Q18 on the same half-bridge from turning on at the same time and allowing shoot-through current to flow.

Here, as shown by the dashed line in FIG. 5(d), if the contactor 43 is switched from OFF to ON when the determination result of the controller 27 switches from normal to abnormal, the output of FIG. (e) The start of output of the gate drive signal is delayed. For this reason, in the present embodiment, in order to minimize the delay in starting the output of the gate drive signal, as shown by the solid line in FIG. 43 is turned on.

When the MOSFETs Q15 to Q18 of the secondary side full bridge circuit BR2 are turned on and off with the gate drive signal shown in FIG. An electromotive force is generated. This induced electromotive force changes in a pattern corresponding to the gate drive signal of FIG. 5(e), as shown in the timing chart of FIG. 5(f).

In addition, due to the magnetic flux generated by the current flowing through the secondary coil of the transformer L, the current also flows through the primary coil of the transformer L. This current also changes in the same pattern as the current flowing through the secondary coil, and an induced electromotive force is generated in the primary coil. This induced electromotive force, as shown in the timing chart of FIG. 5(g), has a pattern corresponding to the gate drive signal of FIG. Change.

The induced electromotive force of FIG. 5(g) generated in the primary side coil of the transformer L is full-wave rectified by the diode bridge circuit formed in the primary side full bridge circuit BR1 by the parasitic diodes of the MOSFETs Q11 to Q14 which are all turned off. . Therefore, as shown in the timing chart of FIG. 5(h), the voltage across the terminals of the DC link capacitor C2 connected to the primary side full bridge circuit BR1 is induced by the induced electromotive force of FIG. Gradually increases from the point of occurrence.

However, the voltage across the terminals of the DC link capacitor C2 is saturated as the charge stored in the DC link capacitor C2 approaches the capacity of the DC link capacitor C2. When the voltage across the terminals of the DC link capacitor C2 does not rise due to saturation, it becomes difficult for new charges to accumulate in the DC link capacitor C2.

Therefore, as shown in FIG. 4, the controller 27 confirms whether or not the rate of increase of the inter-terminal voltage of the DC link capacitor C2 has fallen below the second judgment value ref2 (step S5). The second judgment value ref2 is a reference value for judging whether or not the DC link capacitor C2 has reached a saturation state in which it is difficult to accumulate new charges, based on the rate of increase in the voltage across the terminals of the DC link capacitor C2. . The increase rate of the voltage between the terminals of the DC link capacitor C2 can be determined by any method such as a change in the measured voltage between the terminals of the DC link capacitor C2, a change in the leakage magnetic flux of the primary coil of the transformer L, or the like. can be obtained by

If the rate of increase of the voltage across the terminals of the DC link capacitor C2 has not fallen below the second judgment value ref2 (NO in step S5), the series of processes is terminated. On the other hand, when the rate of increase is less than the second judgment value ref2 (YES in step S5), the controller 27 drives the MOSFETs Q11 to Q14 of the primary side full bridge circuit BR1 (step S7), and then performs a series of processes. exit.

At this time, the controller 27 alternately turns on and off the high-side and low-side MOSFETs Q11, Q12, Q13, and Q14 in each half bridge of the primary side full bridge circuit BR1 with a dead time for preventing the generation of through current interposed therebetween. Let

The cycle in which the MOSFETs Q11 and Q12 of one half bridge are alternately turned on and off is shifted by half a cycle from the cycle in which the MOSFETs Q13 and Q14 of the other half bridge are alternately turned on and off. Therefore, the MOSFETs Q12 and Q13 are turned off during the turn-on period of the MOSFETs Q11 and Q14, and the MOSFETs Q11 and Q14 are turned off during the turn-on period of the MOSFETs Q12 and Q13.

Further, the controller 27 drives the MOSFETs Q11 to Q14 of the primary side full bridge circuit BR1 in a pattern in which the primary side full bridge circuit BR1 operates as a booster circuit. When the primary side full bridge circuit BR1 is operated as a booster circuit, the output voltage (the voltage between the terminals of the DC link capacitor C2) is ) will be boosted.

The primary side full bridge circuit BR1 can be operated as a booster circuit by selecting a combination of MOSFETs Q11 to Q14 used as transistors and MOSFETs Q11 to Q14 used as parasitic diodes. Also, by gradually changing the turn-on period of each of the MOSFETs Q11 to Q14, the primary side full bridge circuit BR1 can be operated as a booster circuit.

Therefore, the controller 27 outputs a gate drive signal having a pattern to operate the primary side full bridge circuit BR1 as a booster circuit to the gate drive circuits of the MOSFETs Q11 to Q14 to drive the MOSFETs Q11 to Q14. The timing chart of FIG. 5(i) shows the gate drive signal pattern for gradually changing the turn-on period of each of the MOSFETs Q11 to Q14.

When the controller 27 detects the saturation of the DC link capacitor C2, for example, the controller 27 outputs the gate drive signal shown in FIG. The voltage across C2 can be raised again. As a result, the charge accumulation in the DC link capacitor C2 can be continued.

Further, in step S9, which proceeds when the DC input voltage has not risen to the first judgment value ref1 (NO), the controller 27 controls each of the primary side full bridge circuit BR1 and the secondary side full bridge circuit BR2 during driving. Stop the MOSFETs Q11 to Q18. Then, the series of processing ends.

The charge accumulated in the DC link capacitor C2 by natural discharge after the rotation of the propulsion motor M is stopped can be discharged, for example, by natural discharge after the rotation of the propulsion motor M is stopped. .

Thus, in this embodiment, when abnormal electrical energy is generated in the propulsion motor M due to an abnormality during rotation, the input side of the power module 31 is connected to the DC link capacitor C2 of the plug-in charger CHG. An electric circuit is formed by the controller 27 .

That is, when the main relay 3 is turned off or the operation of the power module 31 is stopped while the propulsion motor M is rotating, the input side of the power module 31 is connected to the DC link capacitor C2 via the DCDC converter 39 of the plug-in charger CHG. connected to Electric energy generated in the propulsion motor M due to an abnormality during rotation of the propulsion motor M is stored as electric charge in the DC link capacitor C2 of the plug-in charger CHG.

Therefore, even if the capacity of the smoothing capacitor 29 is not increased, an abnormally high voltage is applied to the smoothing capacitor 29 or the IGBTs Q1 to Q6 of the power module 31 by the electrical energy generated in the propulsion motor M due to the occurrence of an abnormality during rotation. can be prevented.

When the voltage across the terminals of the DC link capacitor C2, which rises due to the connection to the input side of the power module 31, saturates, the DC voltage applied to the DC link capacitor C2 is boosted by the primary side full bridge circuit BR1. , can be omitted. However, if this configuration is adopted, it is possible to allow the DC link capacitor C2 to absorb more electric energy generated in the propulsion motor M due to an abnormality occurring during rotation.

Further, the drive pattern of each of the MOSFETs Q11 to Q18 of the DCDC converter 39 when an electric circuit connecting the input side of the power module 31 to the DC link capacitor C2 is formed in the plug-in charger CHG is explained in this embodiment. It may be a different pattern.

Furthermore, when the main relay 3 is turned off due to an abnormality during the rotation of the propulsion motor M, when the controller 27 detects this, in parallel with the processing from step S3 in FIG. Driving may be performed by the controller 27 .

In that case, when the power module 31 starts to be driven with zero torque, the electrical energy generated in the propulsion motor M due to an abnormality during rotation can be absorbed by the switching losses of the IGBTs Q1 to Q6. Therefore, the electric energy stored as electric charge in the DC link capacitor C2 is accumulated during the time lag from when the main relay 3 is turned off due to an abnormality during the rotation of the propulsion motor M to when the power module 31 starts to be driven to zero torque. It is about the inrush component of the electrical energy generated in the propulsion motor M.

Therefore, for example, the electric charge accumulated in the DC link capacitor C2 can be sufficiently discharged by natural discharge after the rotation of the propulsion motor M has stopped.

Furthermore, the present invention is applicable when the DC power of a high-voltage battery, which can be normally charged by a plug-in charger having a DCDC converter while the AC rotating machine is stopped, is converted into AC power by an inverter and supplied to the rotating machine. Can be widely applied.

INDUSTRIAL APPLICABILITY The present invention can be used in an inverter that converts power between a DC power supply and an AC rotating machine.

1 Power control unit 3 Main relay (M/R, contactor)
5 vehicle integrated controller 7 charging cable for quick charger 9 connector 11 charging cable for normal charging 13 connector 15 plug 17 control box 19 junction box (J/B)
21 DCDC converter 23 inverter unit 25 discharge circuit 27 controller 28 power path 28N negative (N) line of power path 28P positive (P) line of power path 29 smoothing capacitor 31 power module (inverter)
31N Negative pole (N pole) line of power module 31P Positive pole (P pole) line of power module 31U, 31V, 31W Output line of power module 33 Motor controller 35 Drive circuit 37 Discharge resistor 39 DCDC converter of plug-in charger 41 High frequency Filter 43 Contactor 45 Voltage sensor ACC Auxiliary device BR1 Primary side full bridge circuit BR2 Secondary side full bridge circuit C2 DC link capacitor C3 High frequency filter capacitor CHG Plug-in charger CP Commercial power port HB High voltage battery HBP High voltage battery Port L Transformer L3 High frequency filter coil LB Low voltage battery LBP Low voltage battery port M Propulsion motor (rotating machine)
PP Power supply port Q1 to Q6 IGBT
Q11 to Q18 MOSFET (semiconductor switching element)
QC Quick charger QP Quick charge port ref1 First judgment value (judgment value of inverter overvoltage state)
ref2 Second judgment value (judgment value of saturated state of DC link capacitor)
SP Signal port VCC Power supply voltage

Claims (3)

A DCDC converter (a DCDC converter ( 39) and
a DC link capacitor (C2) connected to the input side of the DCDC converter (39);
a sensor (45) for detecting a voltage between inputs of the inverter (31);
When the detected voltage of the sensor (45) is equal to or higher than the judgment value (ref1) of the overvoltage state of the inverter (31), the operation of the DCDC converter (39) is controlled to control the input of the inverter (31). a controller (27) forming an electric circuit on the DCDC converter (39) connecting the side and the DC link capacitor (C2);
with
The DCDC converter (39) is an isolated type having, on the output side, a secondary side full bridge circuit (BR2) connected to the secondary side of a transformer (L) to which the DC link capacitor (C2) is connected to the primary side. a DCDC converter,
The controller (27) sets a dead time for each semiconductor switching element (Q15 to Q18) on the high side and low side of each half bridge by shifting half a period between the half bridges of the secondary side full bridge circuit (BR2). sandwiching and alternately turning on and off to form the electric circuit on the DCDC converter (39),
The DCDC converter (39) has, on the input side, a primary side full bridge circuit (BR1) connected to the primary side of the transformer (L), and the controller (27) controls the primary side full bridge circuit ( BR1) operates as a booster circuit in which the output voltage is boosted with respect to the input voltage, and the high-side and low-side semiconductor switching elements (Q11 to Q14) of each half bridge of the primary side full bridge circuit (BR1) ) on and off respectively,
Inverter protection device. The controller (27) shifts the phase between the half bridges of the primary side full bridge circuit (BR1) by half a cycle, gradually increases the on-duty ratio, and performs high-side and low-side semiconductor switching of each half bridge. 2. The inverter protection device according to claim 1, wherein the elements (Q11 to Q14) are alternately turned on and off with dead time intervening . The controller (27) controls the primary side full when the rate of increase of the voltage across the DC link capacitor (C2) is less than a saturation state determination value (Ref2) of the DC link capacitor (C2). 3. The inverter protection device according to claim 1 , wherein the high-side and low-side semiconductor switching elements (Q11 to Q14) of each half bridge of the bridge circuit (BR1) are turned on and off according to the pattern .

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