JP2018207684A - Method and apparatus for discharging smoothing capacitor - Google Patents

Abstract

To provide an apparatus for discharging a smoothing capacitor, capable of discharging the smoothing capacitor in a short time without increasing discharge resistance.SOLUTION: A discharge circuit 15 determines whether or not a voltage time change rate between both end voltages of a smoothing capacitor 12 is less than a predetermined value regardless of the normality/abnormality of a contactor 16. The discharge circuit discharges to a discharging resistance 20 by a discharge current command having a first level when the voltage time change rate between both end voltages of the smoothing capacitor 12 is equal or less than the predetermined value and discharges to the discharging resistance 20 by a discharge current command having a second level larger than the first level when the voltage time change rate between both end voltages of the smoothing capacitor 12 is more than the predetermined value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a smoothing capacitor discharging method and a discharging device in a power converter.

  A voltage source inverter (abbreviated as an inverter) is a power conversion device that converts a DC voltage into an AC voltage, and is widely used for variable-speed drive applications of AC motors. In recent years, it is also one of the core components of hybrid electric vehicles and electric vehicles that expand the market scale against the backdrop of growing environmental awareness.

  In these automobile applications, in particular, in order to protect the passenger from danger caused by some trouble, various abnormality detection means are provided, and the system is shifted to a safe operation state according to the abnormality detection result.

  Further, when the DC voltage supplied to the inverter exceeds 60V, the power consuming means for discharging the charge of the smoothing capacitor connected in parallel to the inverter within a predetermined time in order to remove the voltage ripple associated with the switching operation. Is provided.

  When the vehicle is stopped by turning off the ignition of the vehicle, or when it is determined that the system is necessary due to an accident, etc., the power consumption means is activated and the smoothing capacitor is discharged. There is no level (less than 60V) to ensure safety.

  Note that at least two means are required to be used as power consumption means (redundancy), and the discharge time is, for example, within 5 s for the first means and less than 60 V within 5 minutes for the second means. There is a need.

  Such a technique is described in, for example, Patent Document 1 and Patent Document 2.

Japanese Utility Model Publication No. 63-29391 Japanese Patent No. 4418318

  Patent Document 1 exemplifies a circuit (discharge circuit) in which a discharge resistor and a circuit in which switch elements are connected in series are connected in parallel to the smoothing capacitor as power consumption means for discharging the charge of the smoothing capacitor within a predetermined time. It is described that some kind of control is performed.

  However, Patent Document 1 does not describe details of control.

  On the other hand, in Patent Document 2, for example, a method for controlling the discharge circuit exemplified in Patent Document 1 is shown in detail. According to this method, the voltage of the smoothing capacitor is detected, and the ignition of the vehicle is turned off, so that a predetermined time is given based on the time when an open command of the contactor connected in series between the DC battery and the inverter is given. A change in the voltage value of the smoothing capacitor detected every time is calculated, and the result is compared with a predetermined threshold value to determine whether or not the capacitor discharge is normally performed.

  As a result, for example, when the contactor breaks down and forms a closed circuit against the command, it can be determined that there is an abnormality, and in that case, the discharge operation of the smoothing capacitor is stopped, thereby causing a defect in the discharge resistance. Generation (burnout due to overheating, etc.) can be prevented in advance.

  However, the method described in Patent Document 2 requires complicated processing such as calculating the voltage change of the smoothing capacitor and comparing it with a threshold value, and a predetermined time is required for confirming whether it is normal or abnormal. .

  In addition, in order for the host controller to make a contactor abnormality determination, it may be required to continue discharging during that period. This is because the diagnosis time is determined systematically and may be longer than the diagnosis time for each unit.

  And if you set the rated power of the discharge resistance, taking into account the power consumed until the diagnosis result is normal or abnormal, the size of the discharge resistance will increase, and eventually the cost of the inverter will increase and the implementation There was a problem such as an increase in size for.

  An object of the present invention is to realize a smoothing capacitor discharging method and a discharging device capable of discharging a smoothing capacitor in a short time without increasing the discharging resistance. It is controlled to a predetermined value, and it is determined whether the contactor is open or not by a simple method regardless of whether the contactor is normal or abnormal.

  In order to achieve the above object, the present invention is configured as follows.

  In the smoothing capacitor discharging method, the voltage time change rate of the smoothing capacitor is detected, and when the detected voltage time change rate is equal to or less than a certain voltage time change rate, the current flowing from the smoothing capacitor to the power consumer is The discharge current value of 1 level is set, and when the detected voltage time change rate exceeds a certain voltage time change rate, the current flowing from the smoothing capacitor to the power consumer is changed to the first level. The discharge current value of the second level that is larger than the discharge current value of the first level, and the current flowing through the power consumer is set to the discharge current value of the first level or the discharge current value of the second level. Control to be

  In a smoothing capacitor discharge device, a voltage time change rate detection circuit for detecting a voltage time change rate of the smoothing capacitor, and the voltage time change rate detected by the voltage time change rate detection circuit is equal to or less than a constant voltage time change rate. When the current flowing from the smoothing capacitor to the power consumer is set to a first level discharge current value, and the detected voltage time change rate exceeds a certain voltage time change rate, the smoothing capacitor A discharge current command unit for setting a current flowing from the power consumer to a second level discharge current value larger than the first discharge current value, and a current flowing through the power consumer is set to A discharge current control unit that controls the discharge current value at the first level or the discharge current value at the second level.

  A smoothing capacitor discharging method and apparatus capable of discharging the smoothing capacitor in a short time without increasing the discharge resistance can be realized.

It is a block diagram of an example of the motor drive system using the inverter with which the discharge apparatus of the smoothing capacitor of this invention is applied. It is a circuit diagram of the discharge device of the smoothing capacitor concerning Example 1 of the present invention. It is a figure which shows the voltage change at the time of discharge operation of the discharge circuit by Example 1 of this invention. It is a figure which shows the electric current change at the time of discharge operation of the discharge circuit by Example 1 of this invention. It is a principal part of Example 2 of this invention, and is a figure which shows an overtemperature protection circuit and a discharge stop circuit.

  Hereinafter, embodiments of the smoothing capacitor discharging method and discharging apparatus of the present invention will be described in detail with reference to the accompanying drawings.

Example 1
1 is a configuration diagram of an example of a motor drive system using an inverter (power converter) to which a smoothing capacitor discharge device (discharge circuit) according to a first embodiment of the present invention is applied.

  In FIG. 1, a variable speed drive system for automobile use includes a high voltage battery 1, an inverter 2 having a plurality of transistors (Tu, Tv, Tw) and a plurality of diodes (Du, Dv, Dw), an AC motor 3, A DC input voltage detector 4, AC output current detectors 5, 6 and 7, a rotation angle detector 8, a control circuit 9, a gate drive circuit 10, and a power supply 11 necessary for control and gate drive are provided. ing.

  A smoothing capacitor (C0) 12, a capacitor (C1) 13 and a capacitor (C2) 14 connected in series are connected to the inverter 2 in parallel. For example, the smoothing capacitor 12 has a large capacitance of 800 uF, and the capacitors 13 and 14 have a small capacitance of 0.1 uF, respectively.

  The inverter 2 includes a discharge circuit 15 connected in parallel to the smoothing capacitor 12.

  As shown in FIG. 1, an operating voltage is supplied to the control circuit 9 from the switching power supply 11 supplied with, for example, 12V supplied from the low voltage battery 17, and the control circuit 9 performs gate drive control via the gate drive circuit 10. Thus, the inverter 2 is controlled based on a command from a host controller (not shown) so that the output current becomes a predetermined value, and the motor 3 performs an electric operation or a power generation operation.

  The contactor 16 connected in series to the DC bus (+) and the DC bus (−) of the high voltage battery 1 is opened and closed by a high voltage battery controller (not shown), for example, and the high voltage battery 1 is operated during the operation of the vehicle. And the inverter 2 are closed. When the motor 3 is electrically operated, a current flows from the battery 1 to the inverter 2, and when the motor 3 generates electricity, a current flows from the inverter 2 to the battery 1.

  FIG. 2 is a circuit diagram of a smoothing capacitor discharging apparatus according to Embodiment 1 of the present invention.

  In FIG. 2, a discharge circuit (discharge device) 15 and a power supply circuit 30 for driving the same are connected to the DC buses (+) and (−) connected to the smoothing capacitor 12. The power supply circuit 30 uses the power stored in the smoothing capacitor 12 as a power supply.

  The discharge circuit 15 includes a discharge resistor 20 as a power consumer, a switch element 21 for controlling the current flowing from the smoothing capacitor 12 to the discharge resistor 20, a current detection resistor 25, a low-pass filter circuit 23, a current A voltage obtained by passing through the low-pass filter circuit 23 in proportion to the current flowing through the discharge resistor 20 obtained through the detection resistor 25 and a voltage set corresponding to a predetermined current by a voltage dividing resistor are used for the power supply voltage of the discharge circuit 15. As an input, a hysteresis comparator circuit 22 for on / off control of the switch element 21 is provided.

  In the low-pass filter circuit 23, one end of the resistor 23-1 and one end of the capacitor 23-2 are connected and connected to the negative input end of the comparator 22-1, and the other end of the resistor 23-1 is connected to the OP amplifier 23. -3, the other end of the capacitor 23-2 is connected to GND, one end of a resistor 23-4 is connected to the output end of the OP amplifier 23-3, and the other end of the resistor 23-4 And the other end of the resistor 23-5 are connected to the negative input end of the OP amplifier 23-3, and the other end of the resistor 23-5 is connected to GND. .

  In the switch element 21, one end of a resistor 21-2 is connected to the gate terminal of the FET 21-1, the drain of the FET 21-1 is connected to one end of the discharge resistor 20, and the source of the FET 21-1 is the current detection resistor 25. And is connected to the positive input terminal of the OP amplifier 23-3. In the switch element 21, the other end of the discharge resistor 20 is connected to the DC bus (+). The other end of the current detection resistor 25 having one end connected to the source of the FET 21-1 is connected to the DC bus (−).

  In the hysteresis comparator circuit 22, the output terminal of the comparator 22-1 is connected to one end of the hysteresis width setting resistor 22-2 and one end of the hysteresis width setting resistor 22-3, and the other end of the resistor 22-2 is connected to the comparator 22-. The other end of the resistor 22-3 is connected to the positive power source of the discharge circuit 15.

  The low-pass filter circuit 23 includes an OP amplifier 23-3 that can set a predetermined gain by a resistor 23-4 and a resistor 23-5, in addition to a capacitor 23-2 and a resistor 23-1 that determine the frequency characteristics. The detection sensitivity of the current flowing through the discharge resistor 20 can be set.

  The output voltage of the current command setting circuit 24 that outputs a voltage set corresponding to the predetermined current is at a level determined by the voltage division ratio between the resistors 24-1 and 24-2 connected in series with each other, The level is determined by the voltage division ratio of the resistor 24-3 and the output state of the comparator 26-1 of the current command switching circuit 26. One end of the resistor 24-3 is connected to a connection point between the resistor 24-1 and the resistor 24-2.

  The output voltage of the current command setting circuit 24 is supplied to the positive input terminal of the comparator 22-1.

  When the output of the comparator 26-1 is OFF (high impedance between the output terminal and GND), the current command value determined by the resistor 24-1 and the resistor 24-2 is a hysteresis comparator circuit. 22 and the output of the comparator 26-1 is ON (low impedance between the output terminal and GND), the current command value determined by the resistors 24-1 and 24-3 is supplied to the hysteresis comparator circuit 22.

  Here, the resistor 24-3 is set to be sufficiently smaller than the resistor 24-2.

  The negative input terminal of the comparator 26-1 of the current command switching circuit 26 is configured by a resistor 27-4 connected to the capacitor 27-2 in the voltage time change rate detection circuit 27 that detects the voltage time change rate of the smoothing capacitor 12. Connected to the incomplete differentiation circuit. The other end of the resistor 27-3 whose one end is connected to the positive power supply of the discharge circuit 15 is also connected to the negative input end of the comparator 26-1, and the resistor 27-3 and the resistor 27-4 are connected to the comparator 26-1. The input level of the negative input terminal is biased, and the comparator 26-1 of a single power supply operation is connected for the purpose of enabling determination even when the output of the differentiation circuit decreases.

  The positive input terminal of the comparator 26-1 sets a planned value for switching the current command value of the current setting circuit 24 based on the time change rate of the voltage detected by the differentiation circuit. It can be set by the voltage division ratio between the resistors 26-2 and 26-3 connected to the positive input terminal of the comparator 26-1.

  On the other side of the incomplete differentiation circuit constituted by the resistor 27-3 connected to the capacitor 27-2 of the voltage time change rate detection circuit 27, a gain having a signal obtained by dividing the voltage across the smoothing capacitor 12 as an input is input. Since the output terminal of one OP amplifier 27-1 is connected, the time change rate of the voltage indicates the time change rate of the voltage across the smoothing capacitor 12.

  The positive input terminal of the OP amplifier 27-1 is connected to a connection point between a resistor 27-6 and a resistor 27-5 that divides the voltage across the smoothing capacitor 12. The negative input terminal of the OP amplifier 27-1 is connected to the output terminal of the OP amplifier 27-1.

  The power supply circuit 30 includes a resistor 30-1 for limiting a current, a Zener diode 30-2 connected in series to obtain a predetermined substantially constant voltage, and a ripple removing capacitor 30 connected in parallel thereto. -3.

  The current command setting circuit 24 and the current command switching circuit 26 constitute a discharge current command unit.

  Further, the switch element 21, the hysteresis comparator circuit 22, and the low-pass filter circuit 23 cause the current flowing through the discharge resistor 20 that is a power consumer to have a set first level discharge current value or a second level. A discharge current control unit is configured to control the discharge current value.

  FIG. 3 is a diagram illustrating a voltage change during the discharge operation of the discharge circuit 15 according to the first embodiment of the present invention, and FIG. 4 illustrates a current change during the discharge operation of the discharge circuit 15 according to the first embodiment of the present invention. FIG. FIG. 3 and FIG. 4 show the results of simulating the voltage across the DC buses (+) and (−) and the current flowing through the discharge resistor 20 using SPICE (simulation program). The results shown in FIGS. 3 and 4 show that the capacitance C0 of the smoothing capacitor 12 is 800 uF, the discharge resistor 20 is 800Ω, the current detection resistor 25 is 0.2Ω, and the OP amplifier 23-3 of the low-pass filter circuit 23 that obtains a current detection signal. The gain was 36.

  The voltage reference (current command) to be compared by the hysteresis comparator circuit 22 was set to 130 mV (18 mA) when the time change rate of the voltage was lower than a predetermined value, and 2315 mV (320 mA) otherwise.

  The predetermined value of the time change rate of the voltage was set to be equal to or less than the time change rate of the voltage of the smoothing capacitor 12 due to the discharge of 18 mA. In the first embodiment, the predetermined value of the time change rate of the voltage is set as the time change rate of the voltage of the smoothing capacitor 12 due to the discharge of 18 mA, for example, 22.5 V / sec. If the time change rate of the voltage of the smoothing capacitor 12 is 22.5 V / sec or less, the smoothing capacitor 12 is discharged at 18 mA (the set first level discharge current value), and the voltage of the smoothing capacitor 12 is reduced. When the time change rate exceeds 22.5 V / sec, the smoothing capacitor 12 can be set to discharge at 320 mA (a set second level discharge current value). In addition, the initial voltage of the voltage across the smoothing capacitor 12 was set to 550 V, and it was set that the battery contactor 16 was released at time 0 s.

  3 shows the relationship between the voltage across the smoothing capacitor 12 and time, and FIG. 4 shows the relationship between the current flowing through the discharge resistor 20 and time. Referring to FIGS. 4B and 4C which are enlarged views of the time axis shown in FIG. 4A, the current flowing through the discharge resistor 20 by the switch element 21 is controlled in a pulse shape. I understand.

  In FIGS. 4B and 4C, the latter has a wider energization pulse width than the former. In the period shown in FIG. 4B, the average of the pulse current is about 18 mA, and in the period shown in FIG. 4C, the average is about 300 mA.

  In the hysteresis width for controlling the set switch, the switching frequency is about 500 Hz. During the discharging operation, the loss associated with the switching and the conduction loss of the switch element 21 are added to the power consumption, and the discharging of the smoothing capacitor 12 is facilitated.

  Note that, after 0.95 s, the voltage across the smoothing capacitor 12 fell below 256 V (= 800 Ω × 320 mA), so that the switching element 21 was in an always-on operation mode.

  As shown in FIGS. 3A and 3B, the voltage across the smoothing capacitor 12 drops at approximately 22.5 V / sec due to the discharging operation of the discharging circuit 15. When the detected value of the set time change rate exceeds a predetermined value due to the decrease, the current command is switched to 320 mA, and the time change rate of the voltage across the smoothing capacitor 12 due to the discharge operation increases to about 400 V / sec. And descend. This change occurs approximately at time 0.13 s.

  As a result, due to the discharge currents of 1.8 mA and 320 mA, the voltage across the smoothing capacitor 12 is generally less than 60 V at 1.8 s. It can be seen that the predetermined discharge can be achieved in a short time by applying the first embodiment of the present invention.

  That is, if the time rate of change of the voltage of the smoothing capacitor 12 is 22.5 V / sec or less, the discharge current of the smoothing capacitor 12 is limited to a small value (18 mA) to suppress overheating of the discharge resistor 20. Is that you can. Also, when the rate of time change of the voltage of the smoothing capacitor 12 exceeds 22.5 V / sec, the voltage of the smoothing capacitor 12 decreases rapidly, so the discharge current of the smoothing capacitor 12 is set to a large value (320 mA). By doing so, it is possible to suppress overheating of the discharge resistor 20 and to perform discharge in a short time.

  As described above, according to the first embodiment of the present invention, the discharge circuit 15 has a voltage time change rate of the voltage across the smoothing capacitor 12 regardless of whether the contactor 16 is normal or abnormal. ) If the voltage time rate of change of the voltage across the smoothing capacitor 12 is below a predetermined value, the discharge resistor 20 is discharged with a first level discharge current command, and the voltage across the smoothing capacitor 12 is When the voltage time rate of change exceeds a predetermined value, the discharge resistor 20 is discharged with a second level discharge current command larger than the first level discharge current command. The discharge method and the discharge device of the smoothing capacitor 12 that can discharge the smoothing capacitor 12 in a short time without increasing the size can be realized, and the current flowing through the power consumer such as the discharge resistor 20 is controlled to a predetermined value. Easy In such method, regardless of normal or abnormal contactor 16 determines the open, discharge can be performed appropriately.

  Further, since the power source for operating the discharge circuit 15 is obtained from both ends of the smoothing capacitor 12, if the voltage is 60 V or higher, the discharge is performed even when the low voltage battery 17 that is the power source of the control circuit 9 is disconnected. It also has a unique effect that the operation can be continued.

  Furthermore, since the power source for operating the discharge circuit 15 can discharge the smoothing capacitor 12, it can also be used as a constant discharge circuit.

  Note that it is possible to determine whether or not the contactor 16 is abnormal by a host controller (not shown in the first embodiment).

  Further, at least one of the first level discharge current value and the second level discharge current value so that the voltage across the smoothing capacitor 12 is less than 60 V for a predetermined time, for example, 1.8 s or less. Can also be set.

  In the above-described example, the power supply circuit 30 is provided so that the electric power stored in the smoothing capacitor 12 is used as a drive source for the discharge circuit 15, but the drive source for the discharge circuit 15 is not supplied from the smoothing capacitor 12. A power supply circuit having a separate battery is also possible.

(Example 2)
Next, a second embodiment of the present invention will be described.

  The second embodiment of the present invention is an example in which an overtemperature protection circuit 28 and a discharge stop circuit 29 are added to the discharge circuit 15 of the first embodiment.

  The overtemperature protection circuit 28 is a circuit that stops the discharge operation when the temperature of the discharge resistor 20 exceeds an allowable value due to some failure and performs overtemperature protection of the resistor. The discharge stop circuit 29 is a circuit that can stop discharge by a signal from the external controller 40.

  FIG. 5 is a diagram showing an overtemperature protection circuit 28 and a discharge stop circuit 29, which are the main parts of the second embodiment of the present invention. 5 quotes the switch element 21 and the discharge resistor 20 shown in FIG. 2, which are essential parts for the description of the second embodiment, and omits other portions of the discharge circuit 15. In FIG.

  In FIG. 5, the overtemperature protection circuit 28 includes a comparator 28-1, a thermistor 28-2 for measuring the temperature of the discharge resistor 20, a resistor 28-3 for converting the measured temperature into a voltage change, and a comparator 28-. Resistors 28-4 and 28-5 for setting one overtemperature detection value by dividing the power supply voltage, and resistors 28-6 and 28-7 for providing hysteresis to the operation of the comparator 28-1. And an FET transistor 28-8 for inverting the logic with the output of the comparator 28-1 as an input.

  A connection point between the thermistor 28-2 and the resistor 28-3 is connected to the negative input terminal of the comparator 28-1.

  The connection point between the resistor 28-4 and the resistor 28-5 is connected to the positive input terminal of the comparator 28-1.

  The drain of the FET transistor 28-8 is connected to the gate resistor 21-2 of the switch element 21, and the source of the FET transistor 28-8 is connected to the GND terminal.

  The resistance value of the thermistor 28-2 decreases as the temperature of the discharge resistor 20 rises. As a result, the node voltage between the thermistor 28-2 and the resistor 28-3 decreases. When the voltage value at the connection point between the thermistor 28-2 and the resistor 28-3 falls below the overtemperature detection value, the output between the output of the comparator 28-1 and GND changes from a low impedance to a high impedance state, and the FET transistor 28- When 8 is turned on, the drain-source of the FET transistor 28-8 becomes low impedance, and the gate voltage of the switch element 21 is maintained at substantially zero. That is, the discharge operation to the discharge resistor 20 is stopped.

  Accordingly, when the temperature of the discharge resistor 20 decreases in response to the stop of the discharge operation, the resistance of the thermistor 28-2 increases, and as a result, the connection voltage between the thermistor 28-2 and the resistor 28-3 becomes To increase.

  When the hysteresis width set for the comparator 28-1 is exceeded, the output between the output of the comparator 28-1 and GND changes from a high impedance state to a low impedance state, and the FET transistor 28-8 is turned off, so that the FET transistor 28-8 is turned off. The drain-source of the switch element 21 has a high impedance, and the gate voltage of the switch element 21 changes in response to the output of the comparator 22-1 of the hysteresis comparator circuit 22 of FIG. That is, a discharge operation is performed.

  The discharge stop circuit 29 includes a photocoupler 29-1, the collector of the secondary transistor 29-2 is connected to the gate resistor 21-2 of the switch element 21, and the emitter of the secondary transistor 29-2 is the GND terminal. It is connected to the.

  The primary side photodiode 29-3 of the photocoupler 29-1. It is connected to the GND and the control terminal of the external controller 40 that gives an instruction to stop the discharge operation.

  When current is supplied from the controller 40 to the primary side photodiode 29-3, the collector and emitter of the secondary side transistor 29-2 change to low impedance, and the gate voltage of the switch element 21 is maintained at substantially zero. The That is, the discharge operation is stopped.

  When the supply of current to the primary side photodiode 29-3 is stopped, the collector and emitter of the secondary side transistor 29-2 become high impedance, and the gate voltage of the switch element 21 is the hysteresis shown in FIG. It changes in response to the output of the comparator 22-1 of the comparator 22. That is, a discharge operation is performed.

  The controller 40 may generate a stop command and stop the discharge operation to the discharge resistor 20 due to the occurrence of an abnormality in the contactor 16 or an abnormality in other components (such as other circuits controlled by the controller 40). it can.

  As described above, according to the second embodiment of the present invention, the same effect as that of the first embodiment can be obtained, and when the temperature of the discharge resistor 20 exceeds the allowable value and a stop command is generated from the external controller 40. In this case, it is possible to obtain an effect that the discharge operation can be stopped.

  In the second embodiment of the present invention described above, the overtemperature protection circuit 28 and the discharge stop circuit 29 are provided. However, only one of the overtemperature protection circuit 28 and the discharge stop circuit 29 is provided. It is also possible to configure.

  Further, the present invention can be applied to an inverter connected to a high voltage battery for automobile use, and can also be applied to other uses such as trains and industrial robots.

  In the above-described example, the discharge resistor 20 is used as the power consumer. However, the discharge resistor 20 is not limited to the discharge resistor, and any other member may be used as long as it consumes power. For example, a lamp or a buzzer indicating that a discharge is in progress may be used.

  DESCRIPTION OF SYMBOLS 1 ... High voltage battery, 2 ... Voltage type inverter, 3 ... AC motor, 4 ... DC voltage detector, 5, 6, 7 ... Current detector, 8 ... Rotation position detection 9 ... Control circuit, 10 ... Gate drive circuit, 11 ... Switching power supply, 12 ... Smoothing capacitor, 15 ... Discharge circuit (discharge device), 16 ... Contactor, 17. ..Low voltage battery, 20 ... Discharge resistance, 21 ... Switch element, 21-1 ... FET, 21-2, 22-2, 22-3, 23-1, 23-4, 23-5, 24-1, 24-2, 24-3, 26-2, 26-3, 27-3, 27-4, 27-5, 27-6, 28-3, 28-4, 28-5, 28- 6, 28-7, 30-1... Resistance, 28-2. Thermistor, 22 ... Hysteresis comparator circuit, 22-1, 26-1 ... Comparator, 23 ... Low pass filter circuit, 23-2 ... Capacitor, 23-3 ... OP amplifier, 24 ... Current command setting circuit, 25 ... Current detection resistor, 26 ... Current command switching circuit, 27 ... Voltage time change rate detection circuit, 27-1 ... OP amplifier, 27-2 ... Capacitor, 28 ... Overtemperature protection circuit, 29 ... Discharge stop circuit, 29-1 ... Photocoupler, 29-2 ... Transistor, 29-3 ... Diode, 30 ... Power supply circuit, 40 ···controller

Claims (10)

Detect the voltage time change rate of the smoothing capacitor,
When the detected voltage time change rate is equal to or less than a certain voltage time change rate, the current flowing from the smoothing capacitor to the power consumer is set to a first level discharge current value, and the detected voltage time change rate is set. However, when a certain voltage time change rate is exceeded, the current flowing from the smoothing capacitor to the power consuming body is set to a second level discharge current value larger than the first level discharge current value. ,
A smoothing capacitor discharging method, characterized in that control is performed so that a current flowing through the power consuming body has a set first level discharging current value or a second level discharging current value. The method for discharging a smoothing capacitor according to claim 1,
Detection of the voltage-time change rate of the smoothing capacitor, setting of the current flowing through the power consumer to a first level discharge current value, setting of the current flowing through the power consumer to a second level discharge current value; And the control performed so that the current flowing through the power consuming body becomes the first level discharge current value or the second level discharge current value, uses the power stored in the smoothing capacitor as a drive source. A method for discharging a smoothing capacitor. In the smoothing capacitor discharge method according to claim 1 or 2,
At least one of the first level discharge current value and the second level discharge current value is set such that a voltage across the smoothing capacitor is set to be less than 60 V within a predetermined time. A smoothing capacitor discharging method. In the discharging method of the smoothing capacitor according to any one of claims 1, 2, and 3,
A smoothing capacitor discharging method, wherein when the temperature of the power consumer exceeds an allowable value, the discharging operation of the smoothing capacitor is stopped. In the discharging method of the smoothing capacitor according to any one of claims 1, 2, 3, and 4,
A smoothing capacitor discharging method, wherein a discharging operation of the smoothing capacitor is stopped by a command signal from an external controller. A voltage time change rate detection circuit for detecting a voltage time change rate of the smoothing capacitor;
When the voltage time change rate detected by the voltage time change rate detection circuit is equal to or less than a certain voltage time change rate, the current flowing from the smoothing capacitor to the power consumer is set to a first level discharge current value. When the detected voltage / time change rate exceeds a certain voltage / time change rate, the current flowing from the smoothing capacitor to the power consumer is changed to a second level greater than the first discharge current value. A discharge current command section to set the discharge current value;
A discharge current control unit for controlling the current flowing through the power consuming body to be the set first level discharge current value or the second level discharge current value;
A discharge device for a smoothing capacitor, comprising: In the smoothing capacitor discharging apparatus according to claim 6,
The power supply circuit further includes a power supply circuit that uses the power stored in the smoothing capacitor as a power supply, and the power supply circuit is a drive source for the voltage time change rate detection circuit, the discharge current command unit, and the discharge current control unit. A smoothing capacitor discharge device. In the smoothing capacitor discharge device according to claim 6 or 7,
At least one of the first level discharge current value and the second level discharge current value is set such that a voltage across the smoothing capacitor is set to be less than 60 V within a predetermined time. A smoothing capacitor discharging device. In the smoothing capacitor discharging apparatus according to any one of claims 6, 7, and 8,
A smoothing capacitor discharging apparatus, further comprising a temperature protection circuit for stopping the discharging operation of the smoothing capacitor when a temperature of the power consuming body exceeds an allowable value. In the smoothing capacitor discharging apparatus according to any one of claims 6, 7, 8, and 9,
A discharge device for a smoothing capacitor, further comprising a discharge stop circuit for stopping the discharge operation of the smoothing capacitor in response to a command signal from an external controller.

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