JP5621314B2 - Discharge control device for power conversion system - Google Patents

Description

  The present invention includes a power conversion circuit that includes a series connection body of a high-potential side switching element and a low-potential side switching element, and converts the power of a DC power source into a predetermined power, an output terminal of the power conversion circuit, and the DC power source The present invention is applied to a power conversion system including a capacitor interposed therebetween, and an open / close unit that opens and closes an electric path between the power conversion circuit and the capacitor and the DC power source, and the open / close unit is opened. The discharge voltage of the capacitor is controlled to a specified voltage or less by performing a process of shorting both electrodes of the capacitor by turning on both the high-potential side switching element and the low-potential side switching element. The present invention relates to a discharge control device for a power conversion system including a discharge control means.

  As this type of discharge control device, for example, as shown in Patent Document 1 below, the switching element on the high potential side and the switching element on the low potential side of the inverter are simultaneously turned on, so that the input terminal of the inverter There has also been proposed one in which both electrodes of a connected capacitor are short-circuited to discharge the capacitor. In this control device, the voltage applied to the gate of the IGBT, which is a switching element, is reduced compared to the normal time during discharge control in order to avoid an excessive increase in current flowing when both electrodes of the capacitor are short-circuited. I am letting.

JP 2009-232620 A

  By the way, during the discharge control, the amount of heat generated per unit time of the switching element tends to be very large. For this reason, there exists a possibility that the temperature of a switching element may rise excessively at the time of discharge control.

  The present invention has been made to solve the above-mentioned problems, and its object is to short-circuit both electrodes of the capacitor by turning on both the high-potential side switching element and the low-potential side switching element. It is an object of the present invention to provide a discharge control device for a power conversion system that can suitably suppress a temperature rise of a switching element when performing discharge control of a charging voltage of the capacitor to a specified voltage or less by performing the above process.

  Hereinafter, means for solving the above-described problems and the operation and effect thereof will be described.

According to a first aspect of the present invention, there is provided a power conversion circuit including a series connection body of a switching element on a high potential side and a switching element on a low potential side, which converts predetermined power of a DC power source, an output terminal of the power conversion circuit, The present invention is applied to a power conversion system including a capacitor interposed between DC power supplies, and an opening / closing means for opening and closing an electric path between the power conversion circuit and the capacitor and the DC power supply, and the opening / closing means is opened. Under the circumstances, the charging voltage of the capacitor is reduced to a predetermined voltage or less by performing a process of shorting both electrodes of the capacitor by turning on both the high-potential side switching element and the low-potential side switching element. In a discharge control device of a power conversion system comprising a discharge control means for controlling discharge, the discharge controller is operated by the discharge control means The power supply of at least one of the potential side switching element and the low potential side switching element is a switching power supply, and the discharge control means is powered by the switching power supply based on the output signal of the switching power supply. The short-circuit state between the electrodes is generated a plurality of times by repeating the ON state and the OFF state of the switching element connected to the driving circuit a plurality of times in one discharge control period.

  In the above invention, the discharge period of the capacitor can be controlled in a time-sharing manner by generating a short circuit state of both electrodes of the capacitor a plurality of times, so that the amount of heat generated per unit time of the switching element can be reduced, and consequently switching It can suppress suitably that the temperature of an element rises too much. In particular, in the above-described invention, in one discharge control period, on / off operation is performed by performing on / off operation of at least one of the high potential side switching element and the low potential side switching element based on the output signal of the switching power supply. The command signal transmission means and the like can be simplified.

According to a second aspect of the present invention, in the first aspect , the power source of the low-potential side switching element operated by the discharge control means is a series regulator that steps down the voltage of the capacitor, and the discharge control means The switching power supply, which is the power supply of the driving circuit for the switching element on the high potential side operated by the above-mentioned, has the output of the series regulator as an input.

According to a third invention, in the first or second invention, the discharge control means includes frequency dividing means for dividing a binary signal corresponding to an output signal of the switching power supply. The switching elements connected to the drive circuit powered by the switching power supply are operated on and off in synchronism with each other.

  In the above invention, by providing the frequency dividing means, the frequency of the on / off operation of the switching power supply can be made higher than the frequency of the on / off operation by the discharge control. For this reason, the magnetic components of the switching power supply can be reduced in size.

According to a fourth invention, in the third invention, there is provided temperature control means for operating a frequency dividing ratio by the frequency dividing means to control a temperature rise of the switching element accompanying discharge control by the discharge control means, The control means operates to increase the frequency division ratio while lowering the time ratio of the on time with respect to one cycle of the on state and the off state of the switching element.

  The smaller the time ratio, the larger the ratio of the heat dissipation period to the heat generation period of the switching element. In the above invention, in view of this point, when the frequency division ratio is increased, the duty ratio is decreased, so that it is possible to appropriately suppress the increase in the temperature of the switching element.

According to a fifth invention, in any one of the first to fourth inventions, the high-potential side switching element and the low-potential side switching element are voltage-controlled switching elements, and the discharge control means includes: The voltage applied to the conduction control terminal of each of the switching elements of either one and the other is set so that the current in one of the non-saturation regions is smaller than the other. In addition, while switching either one of the switching states while the other is in the ON state, the both electrodes are short-circuited by repeating the ON state and the OFF state one or more times. It is characterized in that a process for generating a state multiple times is performed.

  In the above invention, since either one of the switching states is switched while the other is in the on state, the switching is performed as if the switching state of one of the other is switched at the time of switching of one of the switching states. A situation in which the current becomes large can be avoided.

In a sixth aspect based on the fifth aspect , the discharge control means includes a frequency dividing means for dividing a binary signal corresponding to an output signal of the switching power supply, and a temperature rise of the switching element accompanying the discharge control. Temperature control means for operating a frequency division ratio by the frequency dividing means to control the frequency division means, and the temperature control means operates the frequency division ratio to feedback control the detected value of any one of the temperatures. Features.

  In the above invention, heat generation of the switching element on the high potential side and the switching element on the low potential side during the discharge control of the capacitor is more remarkable in either one of the switching elements. For this reason, it is possible to suitably avoid that the temperatures of both switching elements become excessively high by performing feedback control using the detected value of the temperature as a control amount.

According to a seventh invention, in the fifth or sixth invention, the other switching element includes a sense terminal that outputs a minute current having a correlation with a current flowing between the input terminal and the output terminal, and the switching element The power source includes a transformer and a power source switching element that opens and closes between the transformer primary coil and the power source, and controls the temperature of the switching element based on a minute current output from the sense terminal. It is characterized by comprising temperature control means for adjusting the voltage application mode to the conduction control terminal of either one of the switching elements by adjusting the output of the secondary coil of the transformer.

  The heat generation of the switching element on the high potential side and the switching element on the low potential side during the discharge control of the capacitor has a correlation with the current flowing therethrough. In the above invention, in view of this point, control is performed so that the temperature of the switching element does not excessively increase based on the current flowing through the switching element during discharge control.

  By the way, even if any one of the switching elements includes a sense terminal, the current detection accuracy may be lowered when the current flowing through the sense terminal is used. In view of this point, the above invention uses a minute current output from the sense terminal of the other switching element.

In an eighth aspect based on the seventh aspect , the output of the secondary coil is adjusted in the primary side in a state in which the on-time ratio with respect to the on / off period of the power switching element is fixed. It is performed as adjustment of the applied voltage of a coil.

  In the above invention, by fixing the duty ratio, the period during which the high-potential side switching element and the low-potential side switching element are turned on based on the period during which the power supply switching element is turned on or off is appropriately Can be determined.

In a ninth aspect based on any one of the fifth to eighth aspects, the discharge control means maintains one of the switching element on the high potential side and the switching element on the low potential side in the on state. The short circuit state of the two electrodes is generated a plurality of times by repeating any one of the ON state and the OFF state a plurality of times.

  When the ON state and OFF state of both the high-potential side switching element and the low-potential side switching element are repeated a plurality of times, the switching state of one of the other switching states is switched when switching one of the switching states. In order to avoid a situation where the through current becomes large as in the case where it is made, it is required to synchronize these. In this regard, in the above-described invention, it is possible to avoid the occurrence of such a request by maintaining either one in the on state.

According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the apparatus includes a determination unit that determines whether or not an abnormality has occurred in a member on which the power conversion system is mounted. An abnormal discharge control for performing a process of short-circuiting both electrodes of the capacitor by turning on both the high-potential side switching element and the low-potential side switching element when it is determined that an abnormality has occurred by the means It is a means.

The system block diagram concerning one Embodiment. The figure which shows the structure of the drive unit concerning the embodiment. The time chart which shows discharge control at the time of abnormality concerning the embodiment. The figure which shows the relationship between a gate applied voltage and an electric current. The figure which shows the characteristic of the minute electric current of a sense terminal. The figure which shows arrangement | positioning of the power supply concerning the modification of the said embodiment.

<One Embodiment>
Hereinafter, a first embodiment in which a discharge device of a power conversion system according to the present invention is applied to a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows the system configuration of this embodiment. The illustrated motor generator 10 is an in-vehicle main machine and is mechanically coupled to drive wheels. Motor generator 10 is connected to high-voltage battery 12 via inverter IV and a parallel connection body of relay SMR2 and resistor 14 and relay SMR1. Here, the high voltage battery 12 has a terminal voltage of, for example, a high voltage of 100 V or higher. Further, among the input terminals of the inverter IV1, a capacitor 16 is connected in parallel to the inverter IV side of the relays SMR1 and SMR2.

  The inverter IV is configured by connecting three series connection bodies of a high-potential side switching element Swp and a low-potential side switching element Swn as power elements in parallel. The connection points of the high-potential side switching element Swp and the low-potential side switching element Swn are connected to the respective phases of the motor generator 10.

  Between the input / output terminals (between the collector and the emitter) of the switching element Swp on the high potential side and the switching element Swn on the low potential side, the free wheel diode FDp on the high potential side and the free wheel diode FDn on the low potential side are connected. The cathode and anode are connected. The switching elements Swp and Swn are both formed of insulated gate bipolar transistors (IGBT). The switching elements Swp and Swn include a sense terminal St that outputs a minute current having a correlation with a current flowing between the input terminal and the output terminal.

  The minute current output from the sense terminal St flows through the shunt resistor 19, and the voltage drop due to this flows in the drive unit DU for driving the switching element Sw # (# = p, n) (only U phase is shown in the figure). Is taken in. The drive unit DU forcibly turns off the switching element Sw # when it is determined that the current flowing between the input terminal and the output terminal of the switching element Sw # is equal to or greater than the threshold current Ith based on the voltage drop amount in the shunt resistor 19. It has a function to make a state.

  On the other hand, the control device 30 is an electronic control device that uses the low-voltage battery 20 as a power source. The control device 30 operates the inverter IV in order to control the control amount of the motor generator 10 as a control target. Specifically, the control device 30 operates based on detection values of various sensors (not shown) and the like, operation signals gup, gvp, gwp for operating the switching elements Swp for the U phase, the V phase, and the W phase of the inverter IV, Operation signals gun, gvn, and gwn for operating the switching element Swn are generated and output. Thereby, the switching elements Swp and Swn are operated by the control device 30 via the drive unit DU connected to their conduction control terminals (gates).

  Incidentally, the high voltage system including the inverter IV and the low voltage system including the control device 30 are insulated by an insulating means such as a photocoupler (not shown), and the operation signal g * # (* = u, v, w , # = P, n) is output to the high voltage system via the insulating means.

  The drive unit DU uses a normal flyback converter FBn as a power source. The normal flyback converter FBn is an isolated converter for supplying the power of the low voltage battery 20 to the upper arm and the lower arm. That is, the energy of the low-voltage battery 20 is stored in the primary coil 32a of the transformer 32 by closing the power switching element 34. At this time, in the secondary coil 32, the current is prevented from flowing by the diode 36. In contrast, when the power switching element 34 is opened, a current flows through the secondary coil 32b, and the normal capacitor 38 is charged. The charging energy of the normal capacitor 38 becomes the energy consumption of the drive unit DU. Although FIG. 1 only shows that the normal-time flyback converter FBn serves as a power source for the U-phase upper and lower arm drive units DU, the power source for the V-phase and W-phase drive units DU is actually used. It is also. For this reason, the number of secondary side coils 32b of the transformer 32 is actually six.

  By the way, the control device 30 detects the collision of the vehicle based on the detection value of the acceleration detecting means (G sensor 22) that detects the acceleration based on the force acting on itself, and forcibly sets the capacitor 16 when the collision is detected. It has a function of performing a process of discharging electrically. During this abnormal discharge control, an abnormality has occurred in the vehicle, and therefore the normal flyback converter FBn may not function as a power source for the drive unit DU. In this embodiment, therefore, a series regulator 40 that steps down the voltage of the capacitor 16 and a discharge flyback converter FBd that uses the output of the series regulator 40 as inputs are separately provided as a power source for the drive unit DU during discharge control during abnormal conditions. Yes.

  The series regulator 40 includes a series connection body of a plurality of (herein, four examples) resistors 44 and a Zener diode 48, which are connected in parallel to the capacitor 16. A plurality of N-channel MOS field effect transistors (switching elements 42) are connected in parallel to the resistor 44. Here, the highest potential resistor 44 is connected between the input terminal of the highest potential switching element 42 and the conduction control terminal, and the conduction control terminals of the intermediate switching element 42 are connected by the resistor 44. ing. Furthermore, the conduction control terminal and the output terminal of the switching element 42 having the lowest potential are connected by a resistor 46.

  The zener diode 48 is connected in parallel with the input terminal and output terminal of the phototransistor on the secondary side of the photocoupler 54. Accordingly, when the photocoupler 54 is turned on, the Zener diode 48 is turned off, and the switching element 42 is turned off. On the other hand, when the photocoupler 54 is turned off, the Zener diode 48 is turned on, and the output voltage of the series regulator 40 rises to the breakdown voltage of the Zener diode 48. When the output current of the series regulator 40 becomes larger than zero, a current flows through the resistor 46, and the switching element 42 having the lowest potential is turned on by the voltage drop. At this time, the resistor 44 functions so that the voltage between the input terminal of the switching element 42 and the conduction control terminal other than the lowest potential is the voltage drop amount of the resistor 46. For this reason, all the switching elements 42 are switched to the on state. At this time, these switching elements 42 operate in a non-saturated region, and the voltage between the output terminal and the input terminal of each switching element 42 is a value obtained by subtracting the breakdown voltage of the Zener diode 48 from the voltage of the capacitor 16. The value is approximately divided by the number of.

  The photodiode on the primary side of the photocoupler 54 is turned on when the abnormal-time discharge command dis output by the control device 30 becomes logic “H”. The abnormal-time discharge command dis is set to logic “H” as long as no collision occurs in a state where the control device 30 is activated. This is a setting for turning on the series regulator 40 even when the control device 30 cannot operate the photocoupler 54 due to a collision.

  On the other hand, the discharge flyback converter FBd stores the output energy of the series regulator 40 in the primary side coil 60a of the transformer 60 when the power switching element 64 is closed. At this time, the current flow is blocked by the diode 66 in the secondary coil 60 b of the transformer 60. Then, when the power supply switching element 64 is opened, a current is output to the discharging capacitor 68 via the diode 66. The turn ratio between the primary side coil 60a and the secondary side coil 60b of the transformer 60 is “1”.

  FIG. 2 shows a configuration of a portion of drive unit DU of U-phase switching element Sw #, particularly using series regulator 40 and discharge flyback converter FBd as a power source.

  As shown in the figure, the output voltage of the series regulator is taken into the regulator 80 via the diode 52 and is controlled to a predetermined voltage here. The output voltage of the regulator 80 is applied to the switching element Swn on the low potential side through the charging switching element 72 and the gate resistor 70. The gate of the switching element Swn on the low potential side is connected to the emitter via the gate resistor 70 and the discharge switching element 74, and this electric path becomes the discharge path of the gate. The switching element for charging 72 and the switching element for discharging 74 are operated by the drive controller for discharging 76 triggered by application of the output voltage of the series regulator 40.

  On the other hand, the clock 82 is for turning on / off the power supply switching element 64 at a predetermined frequency, triggered by application of the output voltage of the series regulator 40. Here, the time ratio of the on time to the on / off cycle is fixed at “½”. The voltage of the discharging capacitor 68 charged by the on / off operation of the power switching element 64 is applied to the charging switching element 72 for the high potential side switching element Swp. The gate resistor 70 for the high potential side switching element Swp and the switching element 74 for discharge are the same as those of the switching element Swn.

  The voltage of the secondary coil 60 b of the transformer 60 is applied to the waveform shaping circuit 84. The waveform shaping circuit 84 generates a voltage waveform similar to the operation signal of the power switching element 64 (the output signal of the clock 82) by shaping the voltage of the secondary coil 60b. The output of the waveform shaping circuit 84 is input to the frequency dividing circuit 86. The frequency divider 86 performs a process of changing the frequency while fixing the pulse width of one of the binary signals output from the waveform shaping circuit 84. The output signal of the frequency divider circuit 86 is input to the discharge drive control unit 78.

  The timer 90 starts a time measuring operation triggered by application of the output voltage of the series regulator 40. The stop processing unit 92 outputs a discharge stop command to the discharge-time drive control unit 76 and the clock 82 when the time measured by the timer 90 reaches a predetermined time. In addition, the voltage of the shunt resistor 19 generated by a minute current output from the sense terminal St of the switching element Swn is applied to the non-inverting input terminal of the comparator 94. The reference voltage Vref of the reference power supply 96 is applied to the inverting input terminal of the comparator 94. Accordingly, in the comparator 94, when the current flowing through the switching element Swn becomes equal to or higher than the threshold current Ith, the stop processing unit 92 is stopped. Is output. As a result, the stop processing unit 92 inhibits the discharge control by flowing a current equal to or greater than the threshold current Ith even before the time counted by the timer 90 reaches a predetermined time.

  The regulator 99 controls the output voltage of the series regulator 40 (the output voltage of the diode 52) to a predetermined value and applies it to the primary coil 60a of the transformer 60. The voltage of the shunt resistor 19 is input to the regulator 99. The higher the voltage, the lower the voltage applied to the primary coil 60a. However, this applied voltage is set lower than the output voltage VH of the regulator 80.

  Further, the output current of the constant current source 98 using the discharging capacitor 68 as a power source is taken into the temperature sensitive diode SD. The output voltage of the temperature sensitive diode SD is input to the frequency dividing circuit 86. The frequency dividing circuit 86 increases the frequency dividing ratio as the output voltage of the temperature sensitive diode SD is lower (the detected temperature is higher).

  FIG. 3 shows an aspect of discharge control based on the abnormal-time discharge command dis. Specifically, FIG. 3A shows the transition of the abnormal discharge command dis, FIG. 3B shows the transition of the output signal of the clock 82, and FIG. 3C shows the output of the temperature sensitive diode SD. FIG. 3D shows the transition of the voltage, FIG. 3D shows the transition of the state of the switching element Swp on the U-phase high potential side, and FIG. 3E shows the state of the switching element Swn on the low potential side of the U-phase. Shows the transition. As illustrated, in this embodiment, the switching element Swp on the high potential side is periodically switched between the on state and the off state while the switching element Swn on the low potential side of the U phase is maintained in the on state. As a result, there is a period in which both the high-potential side switching element Swp and the low-potential side switching element Swn are turned on at the same time. During this period, the two electrodes of the capacitor 16 are connected via the switching elements Swp and Swn. As a result, the capacitor 16 is discharged.

  At this time, since the output voltage of the regulator 99 is lower than the output voltage of the regulator 80, as shown in FIGS. 3 (f) and 3 (g), the gate applied voltage of the switching element Swp on the high potential side is higher. It becomes lower than the gate applied voltage of the switching element Swn on the low potential side. Here, FIG. 3F shows the transition of the gate-emitter voltage Vge of the switching element Swp on the high potential side, and FIG. 3G shows the transition of the gate-emitter voltage Vge of the switching element Swn on the low potential side. Shows the transition.

  According to such a configuration, the switching element Swp on the high potential side is driven in the non-saturation region, and the switching element Swn on the low potential side is driven in the saturation region. Here, as shown in FIG. 4, the saturation region is a region where the voltage between the input terminal and the output terminal of the switching element (collector-emitter voltage Vce) increases in accordance with the output current (collector current Ic). is there. On the other hand, the non-saturated region is a region where the collector-emitter voltage Vce increases without increasing the collector current. The collector current Ic that becomes the non-saturated region increases as the gate applied voltage (gate-emitter voltage Vge) increases.

  For this reason, by lowering the gate applied voltage of the switching element Swp on the high potential side than the switching element Swn on the low potential side, the switching element Swp on the high potential side is less saturated than the switching element Swn on the low potential side. The current in the region is reduced. As a result, the current flowing through the switching element Swp on the high potential side and the switching element Swn on the low potential side by the discharge control is limited to the current in the non-saturated region of the switching element Swp on the high potential side. Note that it is desirable that the current in the non-saturation region of the switching element Swp on the high potential side is set to be less than the threshold current Ith defined by the drive unit DU.

  As shown in FIG. 3D, in the present embodiment, when the temperature of the switching element Swp on the high potential side increases and the output voltage of the temperature sensitive diode SD decreases, the frequency division ratio is increased. The on-time ratio with respect to one cycle of on / off is reduced while fixing one on-time of the switching element Swp on the high potential side. Thereby, the calorific value per unit time can be reduced under the situation where the temperature rises. Incidentally, the reason why the feedback control amount is set to the temperature of the switching element Swp on the high potential side is that most of the amount of heat generated by the discharge control is due to the switching element Swp on the high potential side driven in the non-saturation region. In view of that.

  Further, as shown in FIG. 3F, the gate applied voltage of the switching element Swp was lowered as the discharge current was larger (as the current flowing through the switching element Swn was larger). As a result, the discharge current can be reduced, and consequently the amount of heat generated per unit time can be limited. Note that the current as a parameter for grasping the amount of heat generation is the minute current output from the sense terminal St of the switching element Swn on the low potential side, which is output from the sense terminal St of the switching element Swp on the high potential side. This is because the accuracy is higher than when a minute current is used. FIG. 5 shows a voltage drop amount (sense voltage) in the shunt resistor 19 based on a minute current output from the sense terminal St for each of the switching element Swn driven in the saturation region and the switching element Swp driven in the non-saturation region. The relationship of the dispersion | variation (maximum value MAX, minimum value MIN) is shown. As shown in the figure, the variation in the sense voltage driven in the non-saturation region is very large, and the current detection accuracy is low. For the same reason, only the lower arm is effective for the overcurrent protection function during the abnormal discharge control.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) Based on the output signal of the secondary coil 60b of the transformer 60, the short-circuit state of both electrodes of the capacitor 16 is generated a plurality of times by repeating the ON state and the OFF state of the switching element Swp a plurality of times. Thereby, since the discharge period of the capacitor 16 can be controlled in a time-sharing manner, the amount of heat generated per unit time of the switching elements Swp and Swn can be reduced, and the temperature of the switching elements Swp and Swn excessively increases. This can be suitably suppressed. Further, by performing this on / off operation based on the output voltage of the secondary coil 60b, it is possible to simplify the means for transmitting a command signal for the on / off operation.

  (2) The frequency dividing circuit 86 increases the frequency dividing ratio while lowering the time ratio of the ON time with respect to one cycle of the ON state and the OFF state of the switching element Swp. As a result, the ratio of the heat dissipation period to the heat generation period of the switching element can be increased, and as a result, an operation that suitably suppresses an increase in the temperature of the switching element Swp is possible.

  (3) The frequency division ratio was manipulated to feedback control the detected value of the temperature of the switching element Swp driven in the non-saturation region. Thereby, it can avoid suitably that the temperature of both switching element Swp and Swn becomes high too much.

  (4) The gate applied voltage of the switching element Swp was manipulated based on the minute current output from the sense terminal St of the switching element Swn driven in the saturation region. Thus, the amount of current can be controlled while detecting the discharge current with high accuracy, and thus the amount of heat generated per unit time can be controlled.

  (5) The adjustment of the output voltage of the secondary side coil 60b of the transformer 60 is performed by adjusting the voltage applied to the primary side coil 60a in a state where the time ratio of the on time to the on / off period of the power switching element 64 is fixed. Made as an adjustment. Thereby, the ON time of the switching element Swp that is turned ON / OFF according to the output voltage of the secondary coil 60b can be determined easily and appropriately.

(6) The short-circuited state of both electrodes of the capacitor 16 was generated a plurality of times by repeating the ON state and the OFF state of the high potential side switching device Swp a plurality of times while maintaining the low potential side switching device Swn in the on state. Accordingly, in order to avoid a situation in which the through current becomes large as in the case where the switching state of the low potential side switching element Swn is switched at the time of switching the switching state of the high potential side switching element Swp, these There is no requirement to synchronize.
<Other embodiments>
The above embodiment may be modified as follows.
"Temperature control means"
The temperature control means is not limited to means for operating the frequency division ratio while fixing the interval between pulses corresponding to the ON state. For example, the time ratio when the clock is divided by 4 may be set to “1/8” and the time ratio when the clock is divided by 10 may be set to “2/20”. Here, it is desirable to increase the frequency division ratio while decreasing the on-time ratio of the on-off operation to one cycle.

  The operation amount of the temperature feedback control is not limited to the frequency division ratio. For example, it may be the gate applied voltage of the switching element Swp on the high potential side in the above embodiment. For example, the cathode of the temperature sensing diode SD is set to the same potential as the emitter of the switching element Swn on the low potential side, and the output voltage of the regulator 99 is operated by the drive unit DU of the lower arm based on the output of the temperature sensing diode SD. This can be achieved.

  Further, the detected current value as a parameter having a correlation with the heat generation amount is not limited to the output current of the sense terminal St. For example, it may be a value detected by a current sensor.

  Furthermore, the operation amount of the temperature control based on the detected current value is not limited to the gate applied voltage. For example, a frequency division ratio may be used.

  In addition, the parameter for adjusting the gate applied voltage is not limited to the voltage applied to the primary coil 60a of the transformer 60, but for example the time ratio of the on time with respect to the on / off cycle of the power switching element 64. There may be.

The temperature control means may not be provided.
About abnormal discharge control means
As the discharge control means at the time of abnormality, the short-circuit state of both electrodes of the capacitor 16 is achieved by repeating the ON state and the OFF state of the high potential side switching element Swp a plurality of times while maintaining the low potential side switching element Swn in the ON state. The present invention is not limited to processing that generates multiple times. For example, a process of generating a short circuit state of both electrodes of the capacitor 16 a plurality of times by repeating the ON state and the OFF state of the low potential side switching element Swn a plurality of times while maintaining the switching element Swp on the high potential side in an on state. It may be what you do. However, even in this case, the gate applied voltage on the side where the ON state and the OFF state are repeated a plurality of times is set lower, and the operation is performed in the non-saturated region. Further, for example, a process of generating a short-circuit state of both electrodes of the capacitor 16 a plurality of times by repeating a simultaneous on state and a simultaneous off state of the high potential side switching element Swp and the low potential side switching element Swn a plurality of times. It may be what you do. Again, the gate applied voltage is adjusted so that one of the high-potential side switching element Swp and the low-potential side switching element Swn is operated in the non-saturation region. However, at this time, it is desirable to switch the switching state of the operation in the non-saturation region while the operation in the saturation region is in the on state. Further, both the high-potential side switching element Swp and the low-potential side switching element Swn may be turned on only once in the discharge control period. Again, the gate applied voltage is adjusted so that one of the high-potential side switching element Swp and the low-potential side switching element Swn is operated in the non-saturation region.

  Further, the discharge control is not limited to using only the combination of the switching element Swp on the high potential side and the switching element Swn on the low potential side that applies a voltage to one phase of the motor generator 10. For example, the switching element Swp on the high potential side and the switching element Swn on the low potential side of each phase may be switched so as to be sequentially turned on. In this case, it is desirable to use the series regulator 40 and the discharge flyback converter FBd as the power source of each phase drive unit DU during the discharge control.

  Further, the abnormal-time discharge control means is not limited to one that performs discharge control by turning on both the high-potential side switching element Swp and the low-potential side switching element Swn. For example, a means for causing a reactive current to flow through the motor generator 10 may be used.

  Further, the abnormal-time discharge command dis is not limited to the photocoupler 54 being in the OFF state. For example, both the state where the photocoupler 54 is turned off and the state where the power supply to the normal capacitor 38 is interrupted may be established.

Note that the discharge control performed by turning on both the high-potential side switching element Swp and the low-potential side switching element Swn is performed every time the relay SMR1 is switched to the open state, not limited to an abnormal time. May be.
"Power supply for discharge control drive circuit"
The turn ratio of the transformer 60 and the time ratio of the on / off operation of the power switching element 64 may be appropriately changed.

  The switching power supply may be a forward converter. Further, the step-down chopper circuit or the like is not limited to the isolated converter.

The power supplies for both the upper arm and the lower arm may be switching power supplies. This can be constituted by, for example, an isolated converter that uses the charging voltage of the capacitor 16 as an input voltage and has two secondary coils. In this case, for example, the on / off operation of the high potential side switching element Swp may be repeated according to the output voltage of the secondary side coil while maintaining the low potential side switching element Swn in the on state. .
About the drive unit DU
There is no need to provide a function for forcibly turning off the switching element Sw # by exceeding the threshold current Ith.
"About DC-AC converter circuit"
As a DC / AC converter circuit (inverter IV) in which both the high-potential side switching element and the low-potential side switching element are turned on during the discharge control, the circuit between the rotating machine as the in-vehicle main unit and the high-voltage battery 12 is used. It is not limited to mediating power transfer. For example, the transfer of electric power between the high voltage battery 12 and a rotary machine other than the main machine such as a rotary machine provided in the air conditioner may be used.

Further, the DC / AC conversion circuit is not limited to the inverter IV, and may be an H bridge circuit.
"Power conversion circuit"
The power conversion circuit is not limited to the one composed only of the inverter IV. For example, as shown in FIG. 6, a reactor 100, a low potential side switching element Swn connected in parallel to the capacitor 16 via the reactor 100, a free wheel diode FDp, a low potential side switching element Swn, and a free wheel A boost converter CV including a capacitor 102 connected to a series connection body with the diode FDp may be connected to an input terminal of the inverter IV. In this case, the capacitor 102 and the capacitor 16 connected to the output terminal of the boost converter CV are subjected to discharge control, and the voltage of the capacitor 16 is equal to the free wheel diode FDp as the voltage of the capacitor 102 of the boost converter CV decreases. It will be discharged through.

  Further, as shown in FIG. 6, when the high potential side switching element Swp is connected in parallel to the freewheel diode FDp, the discharge control is performed by turning on both of the pair of switching elements of the boost converter CV. Is also possible.

As shown in FIG. 6, in the case where the boost converter CV is provided, it is particularly effective to use the series regulator 40 when the discharge control is performed by the electric energy of the capacitor 102 connected to the output terminal. That is, in this case, the breakdown voltage required between the input terminal and the output terminal can be reduced by increasing the number of switching elements connected in series between the positive electrode of the capacitor 102 and the output terminal. However, even when the boost converter CV is provided, the discharge control may be performed by the electric energy of the capacitor 16.
(others)
The high-potential side switching element Swp and the low-potential side switching element Swn used for discharge control are not limited to IGBTs, and may be field effect transistors such as power MOS field effect transistors.

  The vehicle is not limited to a hybrid vehicle, and may be, for example, an electric vehicle in which the energy resource stored for the in-vehicle main engine is only electric energy.

  The discharge device is not limited to the one mounted on the vehicle, and may be applied to a power conversion system that converts the power of a DC power source provided in a house into AC, for example. In this case, the abnormal time may be a case where an earthquake or the like is detected.

  DESCRIPTION OF SYMBOLS 10 ... Motor generator, 12 ... High voltage battery (one embodiment of DC power supply), 16 ... Capacitor, 30 ... Control device, 40 ... Series regulator, FBd ... Discharge flyback converter, Swp ... High potential side switching element, Swn: Low-potential side switching element Swn, DU: Drive unit.

Claims (11)

A power conversion circuit having a series connection body of a switching element on the high potential side and a switching element on the low potential side and converting the power of the DC power source to a predetermined value, and interposed between the output terminal of the power conversion circuit and the DC power source The high potential is applied to a power conversion system including a capacitor, and an opening / closing unit that opens and closes an electric path between the capacitor and the capacitor and the DC power source, and the switching unit is opened. Discharge control means for controlling the charging voltage of the capacitor to a specified voltage or less by performing a process of shorting both electrodes of the capacitor by turning on both the switching element on the side and the switching element on the low potential side In a discharge control device of a power conversion system comprising:
The power supply of at least one drive circuit of the high potential side switching element and the low potential side switching element operated by the discharge control means is a switching power supply,
The discharge control means repeats an ON state and an OFF state of a switching element connected to a drive circuit powered by the switching power supply a plurality of times in one discharge control period based on an output signal of the switching power supply. the short-circuit state of the electrodes all SANYO generating a plurality of times,
The power source of the drive circuit for the switching element on the low potential side operated by the discharge control means is a series regulator that steps down the voltage of the capacitor,
A discharge control apparatus for a power conversion system, characterized in that a switching power supply, which is a power supply for a driving circuit of the switching element on the high potential side operated by the discharge control means, receives the output of the series regulator as an input . The discharge control unit includes a frequency dividing unit that divides a binary signal corresponding to an output signal of the switching power supply, and a driving circuit that is powered by the switching power supply is synchronized with the divided signal. discharge control device according to claim 1 Symbol placement power conversion system characterized by operating on and off the switching element connected. A power conversion circuit having a series connection body of a switching element on the high potential side and a switching element on the low potential side and converting the power of the DC power source to a predetermined value, and interposed between the output terminal of the power conversion circuit and the DC power source The high potential is applied to a power conversion system including a capacitor, and an opening / closing unit that opens and closes an electric path between the capacitor and the capacitor and the DC power source, and the switching unit is opened. Discharge control means for controlling the charging voltage of the capacitor to a specified voltage or less by performing a process of shorting both electrodes of the capacitor by turning on both the switching element on the side and the switching element on the low potential side In a discharge control device of a power conversion system comprising:
The power supply of at least one drive circuit of the high potential side switching element and the low potential side switching element operated by the discharge control means is a switching power supply,
The discharge control means repeats an ON state and an OFF state of a switching element connected to a drive circuit powered by the switching power supply a plurality of times in one discharge control period based on an output signal of the switching power supply. The short circuit state of both electrodes is generated multiple times,
The discharge control unit includes a frequency dividing unit that divides a binary signal corresponding to an output signal of the switching power supply, and a driving circuit that is powered by the switching power supply is synchronized with the divided signal. A discharge control device for a power conversion system, wherein a connected switching element is turned on / off. A temperature control means for operating a frequency dividing ratio by the frequency dividing means to control a temperature rise of the switching element accompanying discharge control by the discharge control means;
4. The power conversion system according to claim 2 , wherein the temperature control means increases the frequency division ratio while decreasing the time ratio of the ON time with respect to one cycle of the ON state and the OFF state of the switching element. Discharge control device. The high-potential side switching element and the low-potential side switching element are voltage-controlled switching elements,
It said discharge control means have shifted or the other non-current saturation region said to be smaller than that of the other one either, and the voltage applied to the conduction control terminal of the other one of the respective switching elements And switching one of the switching states while the other is in the ON state, and repeating the ON state and the OFF state of either one a plurality of times. The discharge control device for a power conversion system according to any one of claims 1 to 4, wherein a process of generating a short circuit state of the two electrodes a plurality of times is performed. The discharge control means includes a frequency dividing means for dividing a binary signal corresponding to the output signal of the switching power supply, and a frequency dividing ratio by the frequency dividing means for controlling a temperature rise of the switching element accompanying the discharge control. Temperature control means for operating,
6. The discharge control device for a power conversion system according to claim 5, wherein the temperature control means operates a frequency division ratio so as to feedback control the detected value of any one of the temperatures. The other switching element includes a sense terminal that outputs a minute current having a correlation with a current flowing between the input terminal and the output terminal,
The switching power source includes a transformer and a power switching element that opens and closes between a primary coil of the transformer and the power source,
In order to control the temperature of the switching element based on the minute current output from the sense terminal, the voltage of the voltage to the conduction control terminal of either one of the switching elements is adjusted by adjusting the output of the secondary side coil of the transformer. The discharge control device for a power conversion system according to claim 5 or 6, further comprising temperature control means for operating the application mode. A power conversion circuit having a series connection body of a switching element on the high potential side and a switching element on the low potential side and converting the power of the DC power source to a predetermined value, and interposed between the output terminal of the power conversion circuit and the DC power source The high potential is applied to a power conversion system including a capacitor, and an opening / closing unit that opens and closes an electric path between the capacitor and the capacitor and the DC power source, and the switching unit is opened. Discharge control means for controlling the charging voltage of the capacitor to a specified voltage or less by performing a process of shorting both electrodes of the capacitor by turning on both the switching element on the side and the switching element on the low potential side In a discharge control device of a power conversion system comprising:
The power supply of at least one drive circuit of the high potential side switching element and the low potential side switching element operated by the discharge control means is a switching power supply,
The discharge control means repeats an ON state and an OFF state of a switching element connected to a drive circuit powered by the switching power supply a plurality of times in one discharge control period based on an output signal of the switching power supply. The short circuit state of both electrodes is generated multiple times,
The high-potential side switching element and the low-potential side switching element are voltage-controlled switching elements,
The discharge control means applies a voltage to be applied to the conduction control terminal of each of the one and the other switching elements so that the current in one of the non-saturation regions is smaller than the other. By switching one of the switching states while the other is in the on state, and repeating the on state and off state of the one multiple times. The process of generating a short circuit state of the two electrodes a plurality of times,
The other switching element includes a sense terminal that outputs a minute current having a correlation with a current flowing between the input terminal and the output terminal,
The switching power source includes a transformer and a power switching element that opens and closes between a primary coil of the transformer and the power source,
In order to control the temperature of the switching element based on the minute current output from the sense terminal, the voltage of the voltage to the conduction control terminal of either one of the switching elements is adjusted by adjusting the output of the secondary side coil of the transformer. A discharge control device for a power conversion system, comprising temperature control means for operating an application mode. The adjustment of the output of the secondary side coil is performed as the adjustment of the applied voltage of the primary side coil in a state where the time ratio of the on time with respect to the on / off period of the power switching element is fixed. The discharge control device for a power conversion system according to claim 7 or 8 . The discharge control means is configured to repeat either of the on-state and the off-state a plurality of times while maintaining either one of the high-potential side switching element and the low-potential side switching element in the on state. The discharge control device for a power conversion system according to any one of claims 5 to 9 , wherein the short circuit state is generated a plurality of times. A determination means for determining whether or not an abnormality has occurred in a member on which the power conversion system is mounted;
The discharge control unit short-circuits both electrodes of the capacitor by turning on both the high-potential side switching element and the low-potential side switching element when the determination unit determines that an abnormality has occurred. The discharge control device for a power conversion system according to any one of claims 1 to 10 , wherein the discharge control device is an abnormal-time discharge control means for performing a process to be performed.

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