JP2018160954A - Discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge device that can be downsized.SOLUTION: A discharge device H for discharging electric charges of a smoothing capacitor Cd provided in a drive device Dv of a motor M that rotates wheels of a vehicle, comprises: discharging circuit components (R6, Q1)(R7, Q2)(R8, Q3)(R9, Q4) connected in parallel with the smoothing capacitor Cd and current adjustment circuit components (R2, Q5)(R3, Q6)(R4, Q7)(R5, Q8) that adjust respective currents in the discharging circuit components. The discharging circuit components and current adjustment circuit components are formed in pairs, and the plurality of pairs (R6, Q1, R2, Q5)(R7, Q2, R3, Q6)(R8, Q3, R4, Q7)(R9, Q4, R5, Q8) are connected in series.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a discharge device capable of discharging a smoothing capacitor provided in a motor drive device.

  For example, Patent Document 1 discloses a discharge bypass circuit capable of discharging a smoothing capacitor provided in a vehicle motor drive device and a discharge control device including the control circuit. The control circuit has a voltage induced by a motor exceeding a threshold value. The discharge bypass circuit can start discharging. The discharge bypass circuit (discharging device in a broad sense) of Patent Document 1 includes a resistor and a switching element. The switching element is connected in series with the resistor, and switching is performed when an ON signal is input to the switching element. The element is turned on and the smoothing capacitor can be discharged.

Japanese Patent Laid-Open No. 2006-052140

  Since each of the smoothing capacitor and the discharge bypass circuit is connected in parallel with the high-voltage battery B1, the switching element of the discharge bypass circuit of Patent Document 1 is composed of, for example, a high-voltage insulated gate bipolar transistor (IGBT). . Therefore, the discharge bypass circuit (discharge device in a broad sense) having an insulated gate bipolar transistor is increased in size.

  Further, in order to shorten the discharge time of the smoothing capacitor, the resistor of the discharge bypass circuit of Patent Document 1 is composed of, for example, a cement resistor with high power consumption (high heat generation). Therefore, the discharge bypass circuit further having cement resistance is further increased in size.

  The objective of this invention is providing the discharge device which can be reduced in size.

  In the following, in order to easily understand the outline of the present invention, embodiments according to the present invention will be exemplified.

In the first aspect, a discharge device for discharging the electric charge of the smoothing capacitor provided in the motor drive device that rotates the wheels of the vehicle,
A discharge circuit component connected in parallel with the smoothing capacitor;
A current adjusting circuit component for adjusting a current of the discharging circuit component;
The discharge circuit component and the current adjustment circuit component are configured as one set, and a plurality of sets are connected in series.

  In the first aspect, in the discharge device, the discharge circuit component and the current adjustment circuit component are configured as one set, and a plurality of sets are connected in series. Therefore, the voltage applied to one discharge circuit component is a voltage obtained by reducing the voltage applied to the smoothing capacitor in accordance with the number of the plurality of discharge circuit components. The withstand voltage is reduced. Since the breakdown voltage required for each discharge circuit component is reduced, the discharge device can be downsized even if the number of discharge circuit components is increased.

  In the first aspect, in the discharge device, each of the plurality of current adjustment circuit components can adjust the current of the corresponding one discharge circuit component. In other words, in the first aspect, in one set of discharge circuit component and current adjustment circuit component, the current of the discharge circuit component (discharge time of the smoothing capacitor) is adjusted by the current adjustment circuit component. The amount of heat generated by the circuit components is reduced. Since power consumption required for each discharge circuit component is reduced, the discharge device can be downsized even if the number of discharge circuit components is increased.

  In a second aspect subordinate to the first aspect, the plurality of sets of discharging circuit components and current adjusting circuit components are mounted on the same substrate.

  As shown in the second embodiment, when the discharge circuit component is disposed on the substrate, the inventors have found that the increase in the current of the discharge circuit component is caused by the increase in the temperature of the substrate and the accompanying deterioration of the substrate. The circuit component for current adjustment was mounted on the same substrate. As a result, even when the ambient temperature or the outside air temperature of the discharge circuit component is low, the decrease in the temperature of the current adjustment circuit component is suppressed by the heat generated by the discharge circuit component, and the current flowing through the discharge circuit component is increased. Can be suppressed.

  In the third aspect subordinate to the second aspect, the plurality of discharge circuit components and the plurality of current adjustment circuit components are mounted on different regions on the same substrate and arranged adjacent to each other. Is done.

  In the third aspect, the discharge circuit component and the current adjustment circuit component are configured as one set, and the current adjustment circuit component is disposed adjacent to the discharge circuit component. The present inventors have recognized that when the temperature of the current adjustment circuit component is low, the current of the discharge circuit component increases. Since the discharge circuit component generates heat when the current of the discharge circuit component flows, the temperature of the current adjustment circuit component is unlikely to decrease due to the heat generation. Thereby, even if it is the situation where the ambient temperature or outside temperature of a discharge device is low, the increase in the emitted-heat amount of the circuit component for discharge can be suppressed. In other words, the discharge characteristics of the discharge device (current fluctuations in the circuit components for discharge) are not easily affected by the ambient temperature or the outside air temperature.

  In a fourth aspect subordinate to the third aspect, the discharging circuit component includes a discharging transistor and a discharging resistor, and the current adjusting circuit component includes a current adjusting transistor and a current adjusting resistor. The plurality of discharge transistors and the plurality of current adjustment transistors are mounted on the substrate so as to be arranged on different axes.

  In the fourth aspect, since the plurality of discharge transistors and the plurality of current adjustment transistors are mounted on the substrate so as to be arranged on different axes, the current adjustment transistors are close to the discharge transistors. Can be arranged.

  Those skilled in the art will readily understand that the illustrated embodiments according to the present invention can be further modified without departing from the spirit of the present invention.

1 shows a configuration example of a motor drive system including a discharge device according to the present invention. 2A shows an example of a planar layout of the discharge device of FIG. 1, and FIG. 2B shows an explanatory diagram of a range surrounding the discharge transistor of FIG. 2A.

  The best mode described below is used to easily understand the present invention. Accordingly, those skilled in the art should note that the present invention is not unduly limited by the embodiments described below.

  FIG. 1 shows a configuration example of a motor drive system including a discharge device H according to the present invention. In the example of FIG. 1, the motor drive system drives, for example, a three-phase motor M (vehicle motor) that rotates wheels of a vehicle such as an electric vehicle (EV) and a hybrid vehicle (HV). The drive device Dv includes a capacitor Cd, a discharge device H, and a three-phase inverter circuit.

  The three-phase inverter circuit of FIG. 1 can convert DC power supplied from a high-voltage battery B1 of several hundred [V] or more into three-phase driving power and supply the three-phase driving power to the motor M. it can. The smoothing capacitor Cd of FIG. 1 is provided in the previous stage of the inverter circuit, and can suppress fluctuations in the DC voltage (the output voltage of the battery B1) that is the source of DC power and smooth the DC voltage. The discharge device H of FIG. 1 is provided between the smoothing capacitor Cd and the inverter circuit, and can discharge the electric charge of the smoothing capacitor Cd.

  In the example of FIG. 1, the motor drive system further includes a contactor Ca (switching element in a broad sense), and when the contactor Ca is controlled or changed to a closed state by a control unit (not shown), the drive device Dv or a control (not shown) The inverter circuit controlled by the unit can drive the motor M. The motor drive system can further include a converter Cv (DC / DC converter), and the converter Cv boosts the output voltage of the battery B1 (the voltage applied to the smoothing capacitor Cd or the voltage supplied to the inverter circuit). be able to. The discharge device H constantly discharges the electric charge of the smoothing capacitor Cd via the upper and lower power lines (pads Tp1 and Tp2), and the contactor Ca is opened, so that the smoothing capacitor Cd is discharged within a predetermined time. It becomes possible to make a voltage below a predetermined value.

  The discharge device H in FIG. 1 is a circuit component for discharge (R6, Q1, R7, Q2, R8, Q3, R9, Q4) connected in parallel with the smoothing capacitor Cd and a current adjustment for adjusting the current of the discharge device. Circuit components (R2, Q5, R3, Q6, R4, Q7, R5, Q8). The discharge circuit component and the current adjustment circuit component are configured as one set, and a plurality of sets are connected in series (R6, Q1, R2, Q5) (R7, Q2, R3, Q6) (R8). , Q3, R4, Q7) (R9, Q4, R5, Q8). The discharge circuit component has a plurality of discharge elements (R6, Q1), (R7, Q2), (R8, Q3), (R9, Q4) connected in series. For example, one discharge element (R6, R6) is provided. Q1) includes a discharge resistor R6 (typically a chip resistor) and a discharge transistor Q1 (typically a bipolar transistor) connected in series. The discharge device H can further include a resistor R10, where the resistor R10 (typically a chip resistor) is an emitter resistor and can stabilize the current of the discharge device H.

  The current adjustment circuit component has a plurality of current adjustment elements (R2, Q5), (R3, Q6), (R4, Q7), (R5, Q8) connected in series. For example, one current adjustment element (R2, Q5) includes a current adjustment resistor R2 (typically a chip resistor) and a current adjustment transistor Q5 (typically a bipolar transistor) connected in series. The current adjustment transistor Q5 is disposed closest to one corresponding discharge transistor Q1 among the plurality of discharge transistors Q1, Q2, Q3, and Q4, and turns on and off one corresponding discharge transistor Q1. Switching and adjusting the collector current of one corresponding discharge transistor Q1.

  In FIG. 1, the voltage applied to each of the plurality of discharge transistors (for example, the discharge transistor Q1) depends on the number of the plurality of discharge transistors (for example, “4”) applied to the smoothing capacitor Cd. Since the voltage is reduced, the breakdown voltage required for one discharging transistor Q1 is reduced. Since the breakdown voltage required for each of the discharge transistors Q1, Q2, Q3, and Q4 is reduced, the number of discharge transistors (the switching element of the discharge bypass circuit of Patent Document 1 (for example, a high breakdown voltage insulated gate bipolar transistor)) Even if the number is “1”), the discharge device H can be downsized.

  In FIG. 1, the current of the discharge device H (the discharge time of the charge of the smoothing capacitor Cd) is adjusted by the current adjustment circuit components (specifically, adjusted by the current adjustment transistors Q5, Q6, Q7, and Q8). Therefore, the amount of heat generated by the discharging resistors R6, R7, R8, R9 is reduced. Since the power consumption required for each of the discharge resistors R6, R7, R8, and R9 is reduced, the number of discharge resistors (the number of resistors (for example, cement resistors) in the discharge bypass circuit of Patent Document 1) is “ 1).), The discharge device H can be downsized.

  In addition, in FIG. 1, for example, the current adjusting transistor Q5 is disposed, for example, near the discharging transistor Q1. The present inventors have recognized that the current of the discharge device H (the collector current of the discharge transistors Q1, Q2, Q3, Q4) increases when the temperature of the current adjustment transistors Q5, Q6, Q7, Q8 is low. . Since the discharge transistors Q1, Q2, Q3, Q4 generate heat when the discharge transistors Q1, Q2, Q3, Q4 are turned on, the temperature of the current adjustment transistors Q5, Q6, Q7, Q8 decreases due to the heat generation. It is hard to do. Thereby, even if the ambient temperature or the outside temperature of the discharge device H is low, an increase in the amount of heat generated by the discharge resistors R6, R7, R8, R9 can be suppressed. In other words, the discharge characteristics of the discharge device H (the fluctuations in the current of the discharge device H) are hardly affected by the ambient temperature or the outside air temperature.

  2A shows an example of a planar layout of the discharge device H in FIG. 1, and FIG. 2B shows an explanatory diagram of a range AR surrounding the discharge transistor Q1 in FIG. 2A. In the example of FIG. 2A, the discharge device H is disposed on, for example, one substrate Sb, and a plurality of sets (R6, Q1, R2, Q5) (R7, Q2, R3, Q6) (R8, Q3, R4, Q7) (R9, Q4, R5, Q8) discharge circuit components and current adjustment circuit components are mounted on the same substrate Sb. In FIG. 2A, a plurality of discharge circuit components and a plurality of current adjustment circuit components are mounted on different regions on the same substrate Sb and arranged adjacent to each other. In other words, in the plan view of the discharge device H of FIG. 2A, the discharge circuit components (R6, Q1) (R7, Q2) (R8, Q3) (R9, Q4) are the pads TP1 with reference to the line Li1. On the other hand, the current adjustment circuit components (R2, Q5) (R3, Q6) (R4, Q7) (R5, Q8) are arranged on the pad TP2 side (upper side) and discharged. Mounting regions of circuit components (R6, Q1) (R7, Q2) (R8, Q3) (R9, Q4) are circuit components for current adjustment (R2, Q5) (R3, Q6) (R4, Q7) (R5 , Q8) is adjacent to the mounting area.

  In addition, the plurality of discharge transistors Q1, Q2, Q3, and Q4 and the plurality of current adjustment transistors Q5, Q6, Q7, and Q8 are mounted on the substrate Sb so as to be disposed on the same axes B and A, respectively. Is done. Note that the potential of the pad TP1 is higher than the potential of the pad TP2, and when the voltage is applied to the base B of the discharging transistor Q1 with the voltage across the current adjusting resistor R2, the discharging transistor Q1 is turned on, and In addition, the discharge transistors Q2, Q3, and Q4 are also turned on.

  A current flows through the discharge resistor R6. Similarly, a current flows through the discharge resistors R7, R8, and R9. The current applied to the discharge resistor R6 increases and the voltage applied to the base B of the current adjustment transistor Q5 is a threshold value. When this is the case, the current adjustment transistor Q5 is turned on, and similarly, the current adjustment transistors Q6, Q7, and Q8 are also turned on.

  When the current adjustment transistor Q5 is turned on, the voltage at the base B of the discharge transistor Q1 decreases, the discharge transistor Q1 is turned off, and similarly, the discharge transistors Q2, Q3, and Q4 are also turned off. .

  When the current of the discharge resistor R6 decreases and the current of the discharge resistors R7, R8, and R9 also decreases, the current adjustment transistor Q5 is turned off, and similarly, the current adjustment transistors Q6, Q7, and Q8 Is also turned OFF. Thereafter, the discharging transistor Q1 is turned on again, and similarly, the discharging transistors Q2, Q3, Q4 are also turned on again. As described above, the discharge transistors Q1, Q2, Q3, and Q4 are switched ON and OFF by ON / OFF of the current adjustment transistors Q5, Q6, Q7, and Q8, and the switching is repeated. The current of the discharge device H is switched between increasing and decreasing, and the switching is repeated, so that it can be regarded as a constant current, and it can be said that the discharging device H has a constant current circuit.

  In particular, the present inventors have recognized that when the discharge device H is disposed on the substrate Sb, an increase in the current of the discharge device H can cause an increase in the temperature of the substrate Sb and the accompanying deterioration of the substrate Sb. For example, the current adjusting transistor Q5 is disposed near the discharging transistor Q1. As a result, even when the ambient temperature or the outside air temperature of the discharge device H is low, the decrease in the temperature of the current adjustment transistor Q5 is suppressed by the heat generation of the discharge transistor Q1, and the increase in the current flowing through the discharge resistor R6 is suppressed. Can be suppressed. Similarly, the current adjustment transistors Q6, Q7, and Q8 can be disposed near the discharge transistors Q2, Q3, and Q4, respectively, to suppress an increase in current flowing through the discharge resistors R7, R8, and R9.

  Further, the present inventors or those skilled in the art will consider the current adjustment transistors Q5, Q6, Q7, and Q8 in FIG. 2A, for example, while considering the discharge time of the charge of the smoothing capacitor Cd required for the discharge device H. As shown, the characteristics of the circuit elements of the discharge device H (the resistance values of the discharge resistors R6, R7, R8, R9, the resistance values of the current adjustment resistors R2, R3, R4, R5, the resistor R10 (emitter Including the resistance value of the resistance).

  2A and 2B, around the discharge transistor Q1, two adjacent discharge resistors R6, R7 of the plurality of discharge resistors R6, R7, R8, R9 and a plurality of currents are provided. Two adjacent current adjustment resistors R2 and R3 among the adjustment resistors R2, R3, R4 and R5 are arranged. In the range AR surrounding the discharge transistor Q1 by the two adjacent discharge resistors R6 and R7 and the two adjacent current adjustment resistors R2 and R3, specifically, two adjacent regions shown in FIG. One current adjusting transistor Q5 among a plurality of current adjusting transistors Q5, Q6, Q7, Q8 corresponding to the discharging transistor Q1 is arranged on the line Li2 of the matching current adjusting resistors R2, R3. Is preferred. Thereby, the current adjusting transistor Q5 can be disposed closest to the discharging transistor Q1.

  Similarly, in FIG. 2A, two adjacent discharge resistors R7, R8 and a plurality of current adjustment resistors R2, R3, R4, R5 among the plurality of discharge resistors R6, R7, R8, R9. The current adjustment transistor Q6 is disposed within a range surrounding the discharge transistor Q2 by the two adjacent current adjustment resistors R3 and R4. Further, two adjacent discharge resistors R8, R9 among the plurality of discharge resistors R6, R7, R8, R9 and two adjacent current adjustments among the plurality of current adjustment resistors R2, R3, R4, R5. The current adjusting transistor Q7 is disposed within a range surrounding the discharging transistor Q3 by the resistors R4 and R5. Further, the current is applied on the line of two adjacent current adjustment resistors R4 and R5 among the plurality of discharge resistors R6, R7, R8, and R9 or on the line of the current adjustment resistors R5 and R10. An adjustment transistor Q8 is arranged.

  The present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will be able to easily modify the above-described exemplary embodiments to the extent included in the claims. .

  AR ... range, B ... base, C ... collector, Ca ... contactor, Cd ... smoothing capacitor, Cv ... converter, Dv ... drive device, E ... emitter, H ... discharge device, Li1, Li2 ... line, M ... motor, Q1-Q8 ... transistor, R2-R10 ... resistor, Sb ... substrate, Tp1, Tp2 ... pad .

Claims (4)

A discharge device for discharging electric charges of a smoothing capacitor provided in a motor drive device that rotates a wheel of a vehicle,
A discharge circuit component connected in parallel with the smoothing capacitor;
A current adjusting circuit component for adjusting a current of the discharging circuit component;
The discharge circuit component and the current adjustment circuit component are configured to be one set, and a plurality of sets are connected in series.   The discharge device according to claim 1, wherein the plurality of sets of discharge circuit components and current adjustment circuit components are mounted on the same substrate.   The plurality of discharge circuit components and the plurality of current adjustment circuit components are mounted on different regions on the same substrate and are arranged adjacent to each other. Discharge device.   The discharge circuit component includes a discharge transistor and a discharge resistor, and the current adjustment circuit component includes a current adjustment transistor and a current adjustment resistor, and includes a plurality of discharge transistors and a plurality of current adjustments. The discharge device according to claim 3, wherein the transistors for use are mounted on the substrate so as to be arranged on different axes.

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