JP5375052B2 - Inverter discharge device - Google Patents

Description

  The present invention relates to an inverter discharge device.

  One that drives an AC motor with a DC power supply via an inverter is known (Patent Document 1). In this apparatus, before the inverter or motor is maintained, inspected, or repaired, the electric charge accumulated in the smoothing power storage means (smoothing capacitor) is caused to flow through the winding resistance of the motor to be discharged.

Japanese Patent No. 3289567

  However, the conventional discharge device has a problem that the electric charge of the smoothing capacitor cannot be discharged when the motor is detached or when the winding of the motor is disconnected.

The problem to be solved by the present invention is to provide an inverter discharge device capable of discharging the electric charge of the smoothing power storage means regardless of the presence or absence of a motor.

In the present invention, the charge stored in the power storage means of the inverter is caused to flow as a displacement current in the switching element circuit of the inverter, and specifically, a plurality of switching elements on one side of a plurality of pairs of switching elements are turned on. The above problem is solved by alternately operating a plurality of switching elements on the other side to be OFF .

  According to the present invention, since the displacement current (recovery current) flows through the switching element circuit when the switching element is turned on, the charge stored in the storage means can be discharged regardless of the presence or absence of the motor.

  Hereinafter, embodiments of the invention will be described with reference to the drawings.

<< First Embodiment >>
FIG. 1 is a block diagram showing a drive power supply device for an electric vehicle according to the embodiment of the present invention. Although detailed illustration is omitted, the electric vehicle of this example is a vehicle that travels using a three-phase AC power permanent magnet motor 4 as a travel drive source, and the motor 4 is coupled to the axle of the electric vehicle.

The electric vehicle of the present example converts the above-described three-phase AC motor 4, the battery 1 (DC power supply) that is a power source of the motor 4, such as a secondary battery, and the DC power of the battery 1 into AC power. An inverter 3 and a capacitor 5 (storage means) for smoothing DC power are provided, and the battery 1 is connected to the inverter 3 via a relay 2 (switch means).

The relay 2 is driven to open and close by the vehicle controller 11 in conjunction with the ON / OFF operation of the key switch 12 of the vehicle. That is, when the key switch 12 is ON, the relay 2 is closed, and when the key switch 12 is OFF, the relay 12 is opened.

The inverter 3 includes a plurality of switching elements (insulated gate bipolar transistors IGBTs) Tr1 to Tr6 and rectifying elements that are connected in parallel to the switching elements Tr1 to Tr6 and in which a current flows in a direction opposite to the current direction of the switching elements Tr1 to Tr6. (Diodes) D <b> 1 to D <b> 6, which converts the DC power of the battery 1 into AC power and supplies it to the motor 4. In this example, three pairs of circuits in which two switching elements are connected in series are connected in parallel to the battery 1, and each pair of switching elements is connected to the three-phase input portion of the motor 4.

  In the example shown in FIG. 1, switching elements Tr1 and Tr2, switching elements Tr3 and Tr4, switching elements Tr5 and Tr6 are connected in series, and between the switching elements Tr1 and Tr2, the U phase of the motor 4, and the switching element Tr3. And Tr4 are connected to the V phase of the motor 4, and the switching elements Tr5 and Tr6 are connected to the W phase of the motor 4. The positions between the switching elements connected to the phases U, V, and W of the motor 4 correspond to the output means according to the invention. Details of the operation of the inverter 4 will be described later.

A capacitor 5 for smoothing DC power is connected in parallel with the battery 1 between the relay 2 and the inverter 3.

The vehicle controller 11 includes a central processing unit CPU, a read only memory ROM, and a random access memory RAM. The vehicle controller 11 calculates a torque command value T ^* based on an accelerator signal, a brake signal, a shift position signal, and the like of the electric vehicle. And a start request command and a stop request command are output to the motor controller 10. Further, the vehicle controller 11 outputs a control signal for opening and closing the relay 2 between the battery 1 and the inverter 3, and simultaneously outputs relay opening / closing information to the motor controller 10.

The motor controller 10 controls the operation of the inverter 3. That is, the motor controller 10 generates a pulse width modulation (PWM) signal based on the torque command value T ^* from the vehicle controller 11 and outputs it to the gate drive circuit 9. The gate drive circuit 9 performs ON / OFF control of the switching elements Tr1 to Tr6 constituting the inverter 3 based on the generated PWM signal at a predetermined timing.

The gate drive circuit 9 has a function of detecting an overheat abnormality or an overcurrent abnormality state of the switching elements Tr1 to TR6 and outputting an IGBT abnormality signal to the motor controller 10.

The gate drive circuit 9 receives a signal from the voltage sensor 8 that detects the voltage of the capacitor 5, converts the signal into a waveform level that can be recognized by the motor controller 10, and outputs the waveform level signal to the motor controller 10 as a capacitor voltage signal.

When performing the control as described above, the motor controller 10 is an output from a rotor position sensor 7 (for example, a resolver, an encoder, etc., a rotational speed detection means) provided in the motor 4, and the rotor position of the motor 4. A position sensor signal indicating θ, a feedback signal from a current sensor 6 (current detection means) for detecting each phase current Iu, Iv, Iw supplied from the inverter 3 to the motor 4, and a terminal between the capacitors 5 are connected. The capacitor voltage signal from the voltage sensor 8 (voltage detection means) is read.

The above gate drive circuit 9 and motor controller 10 correspond to the control means according to the present invention.

FIG. 2 is a block diagram showing a main part of the motor controller 10. The motor controller 10 of this example includes a current command value calculation unit 21, a current control unit 22, a dq / 3 phase conversion unit 23, a PWM signal generation unit 24, and a 3 phase / dq conversion unit 25. , Θ (phase) calculation unit 26, a rotation speed (electrical angular velocity) calculation unit 27, and a discharge control unit 28.

The current command value calculation unit 21 is based on the torque command value T ^* calculated by the vehicle controller 11 and the rotation speed of the motor 4 calculated by the rotation number calculation unit 27, and the d-axis current command value Id ^* and q A shaft current command value Iq ^* is calculated. Here, the d-axis current is an excitation current component of a three-phase current (Iu, Iv, Iw) flowing through the motor 4, and the q-axis current is a torque current component.

The current control unit 23 is based on the d-axis current command value Id ^* and the q-axis current command value Iq ^*, and the d-axis current Id and the q-axis current Iq input from the three-phase / dq conversion unit 25 described later. Then, the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* are calculated. Specifically, the deviation between the current command value and the actual current ^{(Id * -Id), (Iq} * -Iq) is calculated respectively for the calculated deviation by performing PI (proportional-integral) operation The d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* can be calculated.

The dq / 3-phase converter 23 converts the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* calculated by the current controller 22 into a phase calculated by a θ (phase) calculator 26 described later. Based on θ, it is converted into a three-phase AC voltage command value Vu ^* , Vv ^* , Vw ^* . The converted three-phase AC voltage command values Vu ^* , Vv ^* , Vw ^* are output to the PWM signal generator 24.

The PWM signal generation unit 24 generates a PWM signal for controlling the inverter 3 based on the three-phase AC voltage command values Vu ^* , Vv ^* , Vw ^* and a triangular wave signal (carrier signal).

The three-phase / dq converter 25 converts the current sensor signal (Iu, Iv, Iw) into a d-axis current Id and a q-axis current Iq.

The θ (position) calculation unit 26 calculates the rotation phase θ based on the signal from the rotor position sensor 7. Further, the rotation speed calculation unit 27 calculates the rotation speed (electrical angular velocity) ω by differentiating the rotation phase θ.

The discharge control unit 28 of this example sets a driving condition of a switching element that discharges the electric charge stored in the capacitor 5 when a stop command signal and relay cut-off information accompanying turning OFF of the relay 2 are input from the vehicle controller 11.

Here, both the q-axis voltage command value Vq ^* , which is a torque voltage component, and the d-axis voltage command value Vd ^* , which is an excitation voltage component, are set to 0 (zero) V.

In this example, the q-axis voltage during normal motor current control for driving and controlling the motor 4 and during discharge control for discharging the stored charge of the capacitor 5 such as during maintenance and inspection of the motor 4 is also shown. The command value Vd ^* and the d-axis voltage command value Vd ^* can be switched and selected by a Vd ^* Vd ^* switching signal.

FIG. 3 shows the gate drive from the gate drive circuit to each of the switching elements Tr1 to Tr6 when the discharge controller 28 sets both the q-axis voltage command value Vq ^* and the d-axis voltage command value Vd ^* to 0V. 4 is a timing chart showing signals GUP, GUN, GVP, GVN, GWP, GWN, inverter output terminal voltages Vu, Vv, Vw, and an output current Icap from a capacitor 5; 3 indicates the ON period of the switching element, and DT is a period (dead time) in which the Hi-side switching elements Tr1, Tr3, Tr5 are OFF and the Lo-side switching elements Tr2, Tr4, Tr6 are OFF. Indicates.

The output current Icap from the capacitor 5 is a displacement current (recovery current) generated when the switching elements Tr1 to Tr6 are turned from OFF to ON, and the junction capacitance Cj of the switching elements Tr1 to Tr6 or the rectifying elements D1 to D6. And the current value is obtained by the product of the voltage change amount dV / dt during switching of the switching elements Tr1 to Tr6 (Icap = Cj × dV / dt).

  The displacement current Icap is generated at a frequency at which the Hi side switching elements Tr1, Tr3, Tr5 and the Lo side switching elements Tr2, Tr4, Tr6 are alternately driven, that is, a frequency 2fsw that is twice the carrier frequency fsw of the triangular wave signal. In particular, the discharge time of the capacitor 5 can be shortened by increasing the drive frequency.

The discharge time Tdischarge at this time can be calculated by the following equation 1 when the capacitance of the capacitor 5 is C, the battery voltage is Vdc, and the switching speed of the switching elements Tr1 to Tr6 is dV / dt.

[Formula 1]
Tdischarge = C × Vdc / (∫Icap dt × 2 fsw)
The gate drive signal during the discharge process in this example has a frequency at which the ON period of the Hi-side switching elements Tr1, Tr3, Tr5 and the ON period of the Lo-side switching elements Tr2, Tr4, Tr6 do not overlap each other. . Further, the ON and OFF cycles of the Hi-side switching elements Tr1, Tr3, Tr5 are the same, and the phase difference is also zero. Further, the ON and OFF cycles of the Lo-side switching elements Tr2, Tr4, Tr6 are the same, and the phase difference is also zero.

Next, the discharge process of this example will be described.

FIG. 4 is a flowchart showing the contents of processing performed by the motor controller 10 when the electric vehicle finishes running, that is, when the key switch 12 is turned OFF.

  In step S10, based on the signal input from the vehicle controller 11, it is determined whether or not the relay 2 has been disconnected. If it is determined that the relay 2 has not been disconnected, the process waits in step S10. If it is determined that the relay 2 has been disconnected, the process proceeds to step S20.

In step S20, based on the rotational speed (electrical angular velocity) ω, it is determined whether the rotational speed of the rotor of the motor 4 is a predetermined value or less (near zero). If it is determined that the rotor of the motor 4 is not less than the predetermined number of rotations, the process waits in step S20.

In step S30, it is determined based on the voltage value of the capacitor 5 whether or not the discharge of the electric charge accumulated in the capacitor 5 has been completed. That is, if the capacitor voltage signal detected based on the voltage sensor 8 is lower than the threshold value of the discharge completion voltage, it is determined that the discharge has been completed, and the process proceeds to step S90. Otherwise, the process proceeds to step S40.

Since discharge processing is required when the voltage of the capacitor 5 detected by the voltage sensor 8 is equal to or higher than the discharge completion voltage, the process proceeds to step S40 to stop the PWM signal for driving the switching elements Tr1 to Tr6 of the inverter 3. After canceling the setting, the process proceeds to step S50. The process of step S40 is because a stop command of the PWM drive signal for each of the switching elements Tr1 to Tr6 is output from the vehicle controller 11 to the motor controller 10 by turning off the key switch.

In step S50, the frequency fsw of the triangular wave signal (carrier signal) of the PWM signal generation unit 24 is set higher than in normal current control. For example, when the carrier frequency during normal operation for driving the motor 4 is 5 kHz, this is set to 35 kHz, for example.

Furthermore, in step S50, both the q-axis voltage command value Vq ^* and the d-axis voltage command value Vd ^* output from the discharge control unit 28 are set to 0V. The d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* set to 0 V are converted into a three-phase AC voltage command value Vu ^* based on the rotor phase θ in the dq / 3-phase converter 23. The signals are converted into Vv ^* and Vw ^* , which are output to the PWM signal generator 24. And after starting the output of a PWM signal from the PWM signal generation part 24, it progresses to step S60. By setting both the q-axis voltage command value Vq ^* and the d-axis voltage command value Vd ^* to 0V, the rotation speed of the motor 4 becomes zero, and the motor 4 is prevented from being driven during the discharge process. The

In step S60, the current sensor signals Iu, Iv, Iw from the current sensor 6 are converted into the d-axis current Id and the q-axis current Iq by the three-phase / dq converter 25, and the converted d-axis current Id and Based on the q-axis current Iq, it is determined whether the amount of change of the d-axis current Id and the q-axis current Iq compared to the previous calculation value is equal to or less than a predetermined value (zero or a value near zero). After confirming that the amount of change is zero, that is, the rotor position sensor signal θ, the switching elements Tr1 to Tr6, the rectifying elements D1 to D6, and the gate drive circuit 9 constituting the inverter 3 are not abnormal, the process proceeds to step S70.

In step S60, when the amount of change in the d-axis current Id and the q-axis current Iq is not less than or equal to a predetermined value (zero or near zero), the rotor position sensor signal θ, the switching elements Tr1 to Tr6 constituting the inverter 3, the rectifying element It is determined that an abnormality has occurred in any of D1 to D6 and the gate drive circuit 9, and the process jumps to step S70 and proceeds to step S80, and the discharge process is terminated. Instead of this, when any one of the switching elements Tr1 to Tr6 or the rectifying elements D1 to D6 is determined to be abnormal in operation and the rotational speed of the motor 4 is less than a predetermined value, the abnormal operation is detected. It is also possible to continue the discharge process by driving ON / OFF switching elements other than the switching element determined to be ON.

In step S70, if the discharge duration so far is equal to or longer than a preset discharge specified time, the process proceeds to step S80. If the discharge duration is within the specified discharge time, the process returns to step S60, and the capacitor 5 is continuously discharged until the specified discharge time is exceeded.

In step S80, after stopping the PWM signal that drives each switching element Tr1 to Tr6 of the inverter 3, the process proceeds to step S90. In step S90, the discharging process of the capacitor 5 is terminated.

  In addition, when the relay 2 is short-circuited by welding or the like, there is a possibility that the voltage does not drop below a predetermined voltage (for example, 60 V) even if a certain time (for example, 1 second) elapses after starting the discharge process. Therefore, in step S70 of this example, it is not determined whether or not the discharge has been completed based on the voltage value of the capacitor 5, but it is determined whether or not the discharge duration has exceeded a predetermined specified discharge time. Thereby, even when the relay 2 is short-circuited by welding or the like, the discharge can be stopped. In this case, it is also possible to notify the driver that an abnormality has occurred by a notifying device (not shown).

FIG. 5 is a timing chart showing the state of each component when operating based on the discharge process of FIG. As shown in FIG. 5, when the key switch 12 is turned off, the vehicle controller 11 cuts off the relay 2. After the relay 2 is cut off, the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* are set to zero, so that a displacement current Icap is generated by driving the switching element, and the capacitor 5 is discharged. Is done.

As described above, in the drive power supply device of this example, when discharging the electric charge stored in the smoothing capacitor 5, the d-axis voltage command value Vd ^* and q-axis for the motor 4 are not discharged to the coil of the motor 4. By setting the voltage command value Vq ^* to zero, the motor 4 is brought into a non-rotating state, and in this state, the switching elements Tr1 to Tr6 of the inverter 3 are controlled to be turned on / off, so that the switching element is turned on immediately. The recovery current flowing through Tr1 to Tr6 and the rectifying elements D1 to D6 is used for the discharging process of the smoothing capacitor 5.

As a result, even if the motor 4 is removed or the coil of the motor 4 is disconnected, the charge stored in the smoothing capacitor 5 can be discharged. Further, in the discharge process, the discharge time can be shortened by increasing the frequency of the PWM signal for the switching elements Tr1 to Tr6.

Note that the d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* during the discharge process are PWM signals via the dq / 3-phase converter 23 and the PWM signal generator 24, but these d− It is also possible to directly generate a desired PWM signal without going through the q / 3-phase converter 23 and the PWM signal generator 24.

<< Second Embodiment >>
FIG. 6 is a flowchart showing a processing procedure of a drive power supply device for an electric vehicle according to another embodiment of the present invention. This example is different from the discharge process (FIG. 4) of the first embodiment described above in that step S61 and step S62 are added. Among the hardware configuration and software configuration of the other drive power supply apparatus, the common parts with FIG. 4 are the same as those in the first embodiment, and therefore the description of those parts is incorporated here and the specific description is omitted.

In step S61 of this example, when the capacitor voltage signal detected by the voltage sensor 8 is equal to or higher than a predetermined elapsed voltage, the process proceeds to step S61, and the carrier frequency fsw of the PWM signal is set to a higher frequency. In the processing in steps S61 to S62, the discharge interval by the recovery current is shortened in order to realize a desired discharge time (for example, 1 second) even when the voltage of the capacitor 5 is unexpectedly high and some abnormality occurs. Is. If the capacitor voltage is less than the predetermined elapsed voltage in step S61, the process jumps to step S62 and proceeds to step S70.

Thereby, even when an abnormal high voltage or the like occurs in the capacitor 5, the discharge time of the capacitor 5 can be completed within a predetermined time.

The carrier frequency fsw of the PWM signal in step S50 may be set to a frequency at the time of driving control of the motor 4, and the carrier frequency fsw in step S62 may be set to a higher frequency.

<< Third Embodiment >>
FIG. 7 is a flowchart showing a processing procedure of a drive power supply device for an electric vehicle according to another embodiment of the present invention. This example is different from the discharge process (FIG. 4) of the first embodiment described above in that step S46 and steps S63 and S64 are added. Among the hardware configuration and software configuration of the other drive power supply apparatus, the common parts with FIG. 4 are the same as those in the first embodiment, and therefore the description of those parts is incorporated here and the specific description is omitted.

  In the discharge process of this example, when an abnormality occurs in the rotor position sensor 7, the switching elements Tr1 to Tr6, the rectifying elements D1 to D6, the gate drive circuit 9 and the like constituting the inverter 3, the torque generated in the motor 4 is The discharge process can be continued while suppressing to a minimum.

For example, when the rotational speed is recognized as near zero due to an abnormality in the rotor position sensor 7 even though the rotor of the motor 4 is rotating, the ON period of the switching elements Tr1 to Tr6 is set to the minimum value. By doing so, the amount of current that is supplied to the motor 4 can be minimized.

That is, in step S63, the ON period of the switching elements Tr1 to Tr6 is set to the minimum value, driving is started, and the process proceeds to step S64.

In step S64, previous calculation values of the d-axis current Id and the q-axis current Iq based on the d-axis current Id and the q-axis current Iq obtained by converting the current sensor signals Iu, Iv, and Iw by the three-phase / dq converter 25. It is determined whether or not the amount of change compared to is less than or equal to a predetermined value (a level at which torque is not generated). If it is confirmed that the amount of change is not more than the predetermined value, the process proceeds to step S70. If the amount of change in the d-axis current Id and the q-axis current Iq is not less than the predetermined value, the process proceeds to step S80 and the discharge is stopped.

FIG. 8 is a timing chart showing gate signal waveforms of the switching elements Tr1 to Tr6 in the process of step S63. That is, when the q-axis voltage command value Vq ^* and the d-axis voltage command value Vd ^* are both set to 0 V in the discharge control unit 28, the gate drive signal GUP from the gate drive circuit to the switching elements Tr1 to Tr6. , GUN, GVP, GVN, GWP, GWN, inverter output terminal voltages Vu, Vv, Vw, and output current Icap from capacitor 5 are timing charts.

In FIG. 8, T indicates the ON period of the switching element, and DT indicates a period (dead time) in which the Hi-side switching elements Tr1, Tr3, Tr5 are OFF and the Lo-side switching elements Tr2, Tr4, Tr6 are OFF. .

The gate drive signal during the discharge process in this example has a frequency at which the ON period of the Hi-side switching elements Tr1, Tr3, Tr5 and the ON period of the Lo-side switching elements Tr2, Tr4, Tr6 do not overlap each other. . Further, the ON and OFF cycles of the Hi-side switching elements Tr1, Tr3, Tr5 are the same, and the phase difference is also zero. Further, the ON and OFF cycles of the Lo-side switching elements Tr2, Tr4, Tr6 are the same, and the phase difference is also zero.

Further, the dead time DT is set larger than that in the embodiment shown in FIG.

式２において、モータ線間電圧Ｖｕｖは、モータ回転数と比例するため、デッドタイムＤＴを大きくすれば、モータ４が回転している時の負トルクを抑制することができる。 In the discharge operation by the switching operation of the inverter 3 when the motor 4 is rotating, the condition that the negative torque is not generated in the motor 4 is that the motor current iL flowing from the motor 4 to the capacitor 5 through the Lo-side switching element, The motor current iL flowing into the capacitor 5 from the motor 4 via the rectifying element connected to the Hi-side switching element is not allowed to flow, and this condition is shown in Equation 2. When the motor line voltage is Vuv and the forward voltage of the rectifying elements D1 to D6 is Vf,
[Formula 2]

In Equation 2, since the motor line voltage Vuv is proportional to the motor rotation speed, the negative torque when the motor 4 is rotating can be suppressed by increasing the dead time DT.

In addition, when the gate signal GUN is ON period ton, iL1 current flows into the capacitor 5, and during the OFF period toff, iL2 current flows into the capacitor 5 through the rectifying element. If the motor line voltage at the time is Vuv, iL1 and iL2 can be expressed as Equations 3 and 4.

［式４］

ｉＬ１＝ｉＬ２より、Ｖｄｃは式５で表わされる。 [Formula 3]

[Formula 4]

From iL1 = iL2, Vdc is expressed by Equation 5.

式５より、スイッチングオフ時間ｔoffを大きくする、すなわちデッドタイムＤＴを大きくすることで、昇圧動作の影響を抑制し、モータ線間電圧Ｖｕｖとインバータ直流Ｖｄｃを同等にすることが可能となる。 [Formula 5]

From Equation 5, by increasing the switching off time toff, that is, by increasing the dead time DT, it is possible to suppress the influence of the boosting operation and make the motor line voltage Vuv and the inverter DC Vdc equal.

In addition, as shown in FIG. 8, it turns out that the same displacement current Icap as the 1st Embodiment mentioned above (refer FIG. 3) is obtained at inverter output terminal Vu, Vv, Vw.

As described above, the overheat abnormality or overcurrent abnormality state of the switching elements Tr1 to Tr6 constituting the inverter 3 is input from the gate drive circuit 9 to the motor controller 10 as an IGBT abnormality signal (see FIG. 1). Normally, during the drive control of the motor 4, a procedure for stopping the PWM signal is executed based on the IGBT abnormality signal. However, during the discharge control of this example, the PWM signal is not stopped when the IGBT is abnormal (FIG. 7). Step S45), the gate signal output stop is continued by the gate stop circuit of each switching element provided in the gate drive circuit 9 (not shown).

It is a block diagram which shows the drive power supply device of the electric vehicle which concerns on embodiment of invention. It is a block diagram which shows the principal part of the motor controller of FIG. 2 is a timing chart showing an operation of a discharge process of the drive power supply device shown in FIG. It is a flowchart which shows the discharge processing procedure of the drive power supply device shown in FIG. FIG. 5 is a timing chart showing an operation state of each component during the discharge process of FIG. 4. FIG. It is a flowchart which shows the other example of the discharge processing procedure of the drive power supply device shown in FIG. 7 is a flowchart showing still another example of the discharge processing procedure of the drive power supply device shown in FIG. 1. It is a timing chart which shows the gate signal waveform of the switching element in step S63 processing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery 2 ... Relay 3 ... Inverter 4 ... Motor 5 ... Capacitor 6 ... Current sensor 7 ... Rotor position sensor 8 ... Voltage sensor 9 ... Gate drive circuit 10 ... Motor controller 11 ... Vehicle controller Tr1-Tr6 ... Switching element D1- D6: Rectifying element

Claims (14)

Power storage means for smoothing the output of the DC power supply;
A plurality of pairs of switching elements respectively connected to both terminals of the power storage means;
A rectifying element connected in parallel to each of the switching elements;
A control means for controlling ON / OFF of the switching element to convert the DC power of the DC power source into AC power;
The control means turns on a plurality of switching elements on one side of the plurality of pairs of switching elements so that electric charges stored in the power storage means flow as displacement currents to the switching elements and the rectifying elements, An inverter discharge device, wherein a plurality of switching elements on the side are alternately turned off . The discharge device for an inverter according to claim 1,
The control means causes the switching elements to alternately turn ON / OFF at a frequency such that the ON periods of the paired switching elements do not overlap each other. The discharge device for an inverter according to claim 2,
The inverter discharge device according to claim 1, wherein the control means makes the ON / OFF drive cycles and phases of a plurality of switching elements connected to the same terminal side of the power storage means the same. In the discharge device of the inverter according to any one of claims 1 to 3,
The inverter discharge device according to claim 1, wherein the control means ends the discharge process when a predetermined discharge time has elapsed. In the discharge device of the inverter according to any one of claims 1 to 4,
Switch means for turning on and off the electrical connection between the DC power source and the inverter;
The control means detects whether or not the switch means is connected, and only when the switch means is not connected, the charge stored in the power storage means is displaced to the switching element and the rectifier element. The inverter discharge device controls the ON / OFF operation of the switching element so as to flow as follows. In the inverter discharge device according to any one of claims 1 to 5,
Comprising output means for outputting the AC power converted by the control means to the motor;
The control device sets the excitation voltage command value and torque voltage command value to be output to the motor via the output device to zero, the discharge device for an inverter, The inverter discharge device according to claim 6,
The control means sets the ON / OFF drive frequency for the switching element when discharging the electric charge stored in the power storage means to a frequency higher than the ON / OFF drive frequency for the switching element when driving the motor. A discharge device for an inverter, characterized by being set. The discharge device for an inverter according to claim 6 or 7,
Voltage detecting means for detecting the voltage of the power storage means,
When the voltage of the power storage unit detected by the voltage detection unit is equal to or higher than a predetermined value, the control unit sets an ON / OFF drive frequency for the switching element when discharging the charge stored in the power storage unit. An inverter discharge device characterized in that it is set higher than the ON / OFF drive frequency when the voltage of the power storage means is less than the predetermined value. In the discharge device of the inverter according to any one of claims 6 to 8,
A rotation speed detecting means for detecting the rotation speed of the motor;
The control means is configured such that the charge stored in the power storage means flows as a displacement current to the switching element and the rectifying element only when the rotation speed of the motor detected by the rotation speed detection means is equal to or less than a predetermined rotation speed. Thus, the ON / OFF operation of the switching element is controlled as described above. The discharge device for an inverter according to claim 9,
Comprising current detection means for detecting current flowing in each phase of the motor;
The control means detects a change amount of the current flowing in each phase detected by the current detection means, and based on the change amount, the rotation speed detection means, the switching element, the rectifier element, and the control means An inverter discharge device characterized by determining an operation abnormality. The discharge device for an inverter according to claim 10,
The inverter discharge device according to claim 1, wherein the control means ends the discharge process when it is determined that any one of the switching elements, any of the rectifying elements, or the rotation speed detecting means is abnormal in operation. The discharge device for an inverter according to claim 10,
When the control means determines that any one of the switching elements or the rectifying element is abnormal in operation,
When the rotational speed of the motor detected by the rotational speed detection means is greater than or equal to a predetermined value, the discharge process is terminated, and when the rotational speed of the motor is less than the predetermined value, a switching element that is determined to be abnormal in operation is provided. An inverter discharge device characterized in that the switching elements other than the switching element are driven ON / OFF. The discharge device for an inverter according to claim 10,
The control means sets the ON period of the switching element to a minimum value when the amount of change in the current flowing through each phase detected by the current detection means is a predetermined value or more. Discharge device. The inverter discharge device according to claim 13,
When the amount of change in the current flowing through each phase detected by the current detection means after the ON period of the switching element is set to a minimum value is less than a predetermined value, the control means An inverter discharge device, wherein the ON / OFF operation of the switching element is controlled so that the stored charge flows as a displacement current to the switching element and the rectifying element.

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