JPH06284517A - Motor controller for electric vehicle - Google Patents

Abstract

PURPOSE:To lower surge voltage even when a motor having large capacity is used and the frequency of switching is increased. CONSTITUTION:A substrate 61 with a plate-shaped positive electrode bus 31 and a plate-shaped negative electrode bus 32, a plurality of a pair of current controlled elements electrically connecting the positive electrode bus 31 and the negative electrode bus 32 and selectively conducting switching, and snubber circuits 21-23 being connected to each pair of the current controlled elements on the substrate 61 and absorbing surge voltage generated at the time of the switching operation of the current controlled elements are provided. The snubber circuits 21-23 consist of capacitors CS1-CS6, diodes DS1-DS6 and resistors RS1-RS6, and each element of the snubber circuits 21-23 is connected by plate-shaped conductors LS1-LS6. The positive electrode bus 31 and the negative electrode bus 32 are wide and have large opposed areas, thus reducing wiring inductance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for an electric vehicle.

[0002]

2. Description of the Related Art Conventionally, in an electric vehicle, a DC power source such as a battery is mounted on a vehicle body, for example, and a DC current from the DC power source is converted into a three-phase AC current to be supplied to a motor. I am trying to drive. In this case, a motor is connected to the drive wheels of the electric vehicle, and the torque of the motor is directly controlled to change the vehicle speed.

Then, the current waveform control circuit outputs a pulse width modulation (PWM) signal corresponding to the load condition of the electric vehicle to the base drive circuit, and the base drive circuit outputs the current control element drive signal as a switching signal. It is designed to be output to the inverter bridge. In the inverter bridge, the current control element drive signal corresponds to the pulse width modulation signal, and a power transistor, IG, as a current control element of the inverter bridge.
The BT or the like is driven to convert the DC current from the DC power supply into a three-phase AC current. Then, the three-phase alternating current is supplied to the motor.

In the inverter bridge, in order to reduce the wiring inductance, the positive electrode bus and the negative electrode bus are formed of wide plates, and the positive electrode bus and the negative electrode bus are arranged so that their respective surfaces face each other. (See Japanese Patent Laid-Open No. 4-133669). That is, assuming that the wiring inductance of the inverter bridge is L, the voltage applied between the positive electrode bus and the negative electrode bus is v, and the current flowing between the positive electrode bus and the negative electrode bus is i, at the time of the switching operation of the current control element. A surge voltage ΔV = L · dv / dt = L · di / dt occurs.

The surge voltage ΔV depends on the wiring inductance L of the inverter bridge and dv / dt or di / dt.
Therefore, the surge voltage ΔV can be lowered by reducing the wiring inductance L. By the way, the wiring inductance L exists in all conductors, exists in the positive electrode bus and the negative electrode bus, and has the same characteristic as the resistance. Therefore, the wiring inductance L can be reduced by increasing the cross-sectional areas of the positive electrode bus and the negative electrode bus and reducing the length thereof.

Further, the wiring inductance L can be reduced by increasing the facing area of the conductor through which the current flows in the opposite direction. That is, it is proportional to the distance between the positive electrode bus and the negative electrode bus extending in parallel, and is inversely proportional to the width of the positive electrode bus and the negative electrode bus. Therefore, the wiring inductance L can be reduced by forming the positive electrode bus and the negative electrode bus with a wide plate and disposing them so that the respective surfaces of the positive electrode bus and the negative electrode bus face each other.

In this way, the surge voltage ΔV can be lowered.

[0008]

However, in the above-mentioned conventional inverter bridge, when it is applied to a motor control device of an electric vehicle, a large capacity motor is used as a motor, and therefore a power supply of several hundred volts from a DC power supply is used. A voltage is applied and a current of several hundred amps is supplied, di / d
The i part of t becomes large.

Further, in order to reduce the distortion (distortion) of the current waveform and to reduce the noise generated by the motor, it is necessary to increase the switching frequency by the current control element. The amount of t becomes small. Therefore, di / dt increases, and the surge voltage ΔV increases correspondingly, and the current control element is damaged.

Therefore, in order to protect the current control element, a snubber circuit for absorbing the surge voltage ΔV is connected between the collector and the emitter of the current control element.
The snubber circuit is formed by combining a diode, a capacitor, a resistor, etc., and absorbs the surge voltage ΔV generated during the switching operation of the current control element. However, since the wiring inductance L exists in the conductor of the snubber circuit, the snubber circuit does not function sufficiently. In addition, it becomes difficult to mount the diode, the capacitor, the resistor, etc. that form the snubber circuit, and the workability is reduced.

The present invention solves the above-mentioned problems of the conventional inverter bridge so that the surge voltage can be reduced, and even if a large capacity motor is used or the switching frequency is increased. An object of the present invention is to provide a motor control device for an electric vehicle in which a snubber circuit can be easily mounted and workability can be improved without damaging a current control element.

[0012]

Therefore, in a motor control device for an electric vehicle of the present invention, a substrate provided with a plate-shaped positive electrode bus and a plate-shaped negative electrode bus extending in parallel with the positive electrode bus, and A plurality of pairs of current control elements that electrically connect the positive bus and the negative bus to selectively switch, and a surge voltage that is connected to each pair of current control elements on the substrate and that occurs during the switching operation of the current control elements It has a snubber circuit for absorbing.

The snubber circuit comprises a capacitor, a diode and a resistor, and each element of the snubber circuit is connected by a plate-shaped conductor.

[0014]

According to the present invention, as described above, the motor control device for an electric vehicle includes a substrate having a plate-shaped positive electrode bus and a plate-shaped negative electrode bus extending in parallel with the positive electrode bus. A plurality of pairs of current control elements that electrically connect the positive bus and the negative bus and selectively switch, and surges that are connected to each pair of current control elements on the substrate and that occur during the switching operation of the current control elements. It has a snubber circuit for absorbing the voltage.

The snubber circuit comprises a capacitor, a diode and a resistor, and each element of the snubber circuit is connected by a plate-shaped conductor. In this case, since both the positive electrode bus and the negative electrode bus are plate-shaped, the width is wide and the area where the positive electrode bus and the negative electrode bus face each other is large. Therefore, the wiring inductance of the inverter bridge can be reduced.

As a result, the surge voltage generated during the switching operation of the current control element can be reduced, and even if a large capacity motor is used or the switching frequency is increased, the current control element will not operate. It will not be damaged. Further, since each element of the snubber circuit is connected by the plate-shaped conductor, the wiring inductance of the snubber circuit can be reduced and the snubber circuit can sufficiently function.

Since each element of the snubber circuit can be mounted on the substrate, the positive bus, the negative bus and the snubber circuit can be sub-assembled to improve workability, and motor control of an electric vehicle can be achieved. The manufacturing process of the device can be simplified.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a block diagram of a motor control device for an electric vehicle showing an embodiment of the present invention. In the figure, reference numeral 11 is a brushless motor provided on the vehicle body of the electric vehicle, and in this case, only one motor is shown. The motor 11 is connected to drive wheels (not shown) of an electric vehicle, and includes, for example, a rotor (not shown) made of a permanent magnet having 6 poles, and an electromagnetic coil made of three-phase windings, that is, a stator coil (not shown). Also, 12
Is a DC power supply having a voltage of 240 [V], for example.

A rotor (not shown) of the resolver 15 is coaxially coupled to the rotor shaft 13 of the motor 11,
The absolute position of the magnetic pole of the rotor of the motor 11 can be detected. That is, the resolver 15
A resolver circuit 16 is connected to the resolver circuit 16 and
Applies an AC voltage E _m sin ωt and an AC voltage E _m cos ωt (indicated by x and y in the figure) to the resolver 15, and at the same time applies an AC voltage E _m sin (ωt + θ) from the resolver 15.
Receiving the resolver signal a, the absolute position of the magnetic pole of the rotor is detected, and the excitation position signal b is output to the current waveform control circuit 17.

The current waveform control circuit 17 is provided to supply a three-phase AC current corresponding to a load condition of the electric vehicle, for example, a depression amount of an accelerator pedal (not shown) to the motor 11, and a required current (torque). The U-phase, V-phase, and W-phase pulse width modulation signals d having a duty ratio corresponding to (command) are output to the base drive circuit 28.

The stator coil of the motor 11 is excited by the inverter bridge 18. The inverter bridge 18 is a current controlling element has six power transistors Tr ₁ to Tr ₆ as the base drive circuit 2 to the base of the power transistor Tr ₁ to Tr ₆
The current control element drive signal c from 8 as a switching signal
Is entered. The base drive circuit 28 outputs a pulse width modulation signal d output from the current waveform control circuit 17.
In response to this, the power transistors Tr _{1 to} Tr ₆ are driven.

Further, a current command signal j ₁ , a rotation direction command signal j ₂ , a regenerative signal j ₃ , an operation command for commanding the required current to the current waveform control circuit 17 from an output port of a main computer (not shown). The signal j ₄ etc. is output. A power supply circuit 29 is connected to the DC power supply 12, applies a drive voltage q to the inverter bridge 18, and applies a control power supply voltage r to each control circuit such as the current waveform control circuit 17. .

Reference numeral 30 is a current sensor for a three-phase alternating current supplied to the motor 11. The current sensor 30
Outputs a U-phase current detection signal s and a V-phase current detection signal t to the current waveform control circuit 17. Next, details of the inverter bridge 18 will be described with reference to FIG. FIG. 3 is a detailed view of the inverter bridge in the embodiment of the present invention.

In the figure, 18 is an inverter bridge,
Tr _{1 to} Tr ₆ are power transistors. Power transistors Tr ₁ and Tr ₂ , power transistor T
r ₃ , Tr ₄ and power transistors Tr ₅ , Tr ₆
Respectively form a pair of positive electrode bus 31 and negative electrode bus 32.
To be electrically connected. And the power transistor Tr
_A U-phase current from ₁ and Tr ₂ , a V-phase current from power transistors Tr ₃ and Tr ₄ , and a W-phase current from power transistors Tr ₅ and Tr ₆ to the stator coil of the motor 11. Supplied.

The power transistors Tr _{1 to} Tr ₆ are respectively connected to the diodes D _{1 to} D ₆ which connect between the emitter and the collector. The power transistor T
The current control element drive signal c is input from the base drive circuit 28 to the bases of each of r _{1 to} Tr ₆ , and selectively switches to form the waveforms of the U-phase, V-phase, and W-phase currents.

C ₁ and C ₂ are large smoothing capacitors provided to smooth the voltage waveform on the DC power supply 12 side and cancel the wiring inductance between the DC power supply 12 side and one inverter. Two bridges 18 are provided in parallel, but if a large capacity one is used, only one can be provided. The smoothing capacitors C ₁ and C ₂ are aluminum electrolytic capacitors.

By the way, the power transistor Tr ₁
When Tr ₆ switches, when the current is i, the wiring inductance of the inverter bridge 18 is L, and the time is t, a surge voltage Δv proportional to L · di / dt is generated, and the surge voltage Δv is The voltage is superimposed on the power supply voltage and applied to the power transistors Tr _{1 to} Tr ₆ to generate an overvoltage. Therefore, snubber circuits 21 to 23 are provided in the inverter bridge 18 in order to prevent the overvoltage from being generated by absorbing the surge voltage Δv.

In this case, the power transistor T
In order to absorb the surge voltage Δv generated in r ₁ and Tr ₂ , the snubber circuit 21 uses the power transistors Tr ₃ and Tr 2.
_The snubber circuit 22 is provided to absorb the surge voltage Δv generated in the transistor ₄ , and the snubber circuit 23 is provided to absorb the surge voltage Δv generated in the power transistors Tr ₅ and Tr ₆ .

That is, in the snubber circuit 21, the series circuit of the capacitor C _S1 and the diode D _S1 is connected in parallel to the power transistor Tr ₁ , and the connection portion between the capacitor C _S1 and the diode D _S1 and the negative bus 32 are connected. A resistor R _S1 is connected to. Also, the power transistor T
against r ₂ series circuit of a capacitor C _S2 and the diode D _S2 is connected in parallel, the resistance R _S2 between the connection portion and the positive electrode ugly 31 of the capacitor C _S2 and the diode D _S2 is connected.

[0030] In the snubber circuit 22, the series circuit of a capacitor C _S3 and the diode D _S3 is connected in parallel with the power transistor Tr _3, between the connection portion and the negative electrode ugly 32 of the capacitor C _S3 and the diode D _S3 The resistor R _S3 is connected. Further, a series circuit of a capacitor C _S4 and the diode D _S4 is connected in parallel to the power transistor Tr _4, resistor R _S4 between the connection portion and the positive electrode ugly 31 of the capacitor C _S4 and the diode D _S4 is connected.

[0031] In the snubber circuit 23, the series circuit of a capacitor C _S5 and the diode D _S5 is connected in parallel to the power transistor Tr _5, between the connection portion and the negative electrode ugly 32 of the capacitor C _S5 and the diode D _S5 The resistor R _S5 is connected. Further, a series circuit of a capacitor C _S6 and the diode D _S6 are connected in parallel to the power transistor Tr _6, the resistor R _S6 are connected between the connection portion and the positive electrode ugly 31 of the capacitor C _S6 and the diode D _S6.

Next, the mounting state of the motor control device having the above construction will be described. 1 is a plan view of a motor control device for an electric vehicle showing an embodiment of the present invention, FIG. 4 is a front view of a motor control device for an electric vehicle showing an embodiment of the present invention, and FIG. 5 is a sectional view taken along line AA of FIG. 6 and 6 are cross-sectional views taken along the line BB of FIG.
Is a diagram showing a positive electrode bus in an example of the present invention, FIG. 8 is a diagram showing a negative electrode bus in an example of the present invention, FIG. 9 is a diagram showing a first insulating material in the example of the present invention, and FIG. 1 is a diagram showing a second insulating material in the embodiment of the present invention, FIG. 11 is a diagram showing a third insulating material in the embodiment of the present invention, FIG. 12 is a mounting state diagram of a smoothing capacitor in the embodiment of the present invention, and FIG.
3 is a mounting state diagram of the power transistor in the embodiment of the present invention, FIG. 14 is a side view of the heat dissipation device of the power transistor in the embodiment of the present invention, and FIG. 15 is a front view of the heat dissipation device of the power transistor in the embodiment of the present invention. Is.
7A to 11A are planes,
(B) shows a side surface.

In the figure, 61 is an inverter bridge 1.
8 power transistors Tr _{1 to} Tr ₆ and snubber circuit 2
1 to 23 are a pair of substrates for mounting each element and the like, and include a first insulating material 33, a positive electrode bus 31, a second insulating material 34,
The negative electrode bus 32 and the third insulating material 35 are laminated in order and fixed by bolts and nuts 36 formed of the insulating material. In the figure, only the substrate 61 on the front side is shown. The first insulating material 33 and the third insulating material 35 are provided so that an operator does not touch the positive electrode bus 31 and the negative electrode bus 32 to which a high voltage is applied and a high current flows, and the second insulating material 34. Is provided to insulate between the positive bus 31 and the negative bus 32 to form a capacitance.

Then, the power transistors Tr _{1 to} Tr ₆ are arranged on the substrate 61 and the snubber circuits 21 to 23 are formed. Therefore, the six resistors R _S1 ~
R _S6 , six capacitors C _{S1 to} C _S6 and six diodes D _{S1 to} D _S6 are mounted. The diodes D _{S1 to} D
_S6 is a set of two and is divided into three sets.
5 and 6, in order to secure the insulation distance between the metal part of the fixing component and the positive electrode bus 31 and the negative electrode bus 32 when fixing the resistors R _{S1 to} R _S6 and the capacitors C _{S1 to} C _S6. A spacer 37 formed of an insulating material is attached.

The snubber circuits 21 to 2 are connected to the substrate 61.
Since each element of 3 can be mounted, the positive electrode bus 3
1, the negative electrode bus 32 and the snubber circuits 21 to 23 can be sub-assembled, and the manufacturing process of the motor control device of the electric vehicle can be simplified. Here, in order to reduce the wiring inductance L of the inverter bridge 18, the positive electrode bus 31 and the negative electrode bus 32 through which current flows in the opposite direction are formed by wide plates to widen the widths W ₁ and W _{2 and} to reduce the opposing area. Making it big. Further, the interval between the positive electrode bus 31 and the negative electrode bus 32 extending in parallel is made small.

In this way, the power transistor Tr
_The surge voltage ΔV generated during the switching operation of _{1 to} Tr ₆ can be reduced. A bias circuit (not shown) is provided between the bases and emitters of the power transistors Tr _{1 to} Tr ₆ , but when the wiring inductance L increases, a current flows through the bias circuit to the bases of the power transistors Tr _{1 to} Tr ₆ . And noise is generated in the current control element drive signal c input to the base. In this embodiment, the wiring inductance L
Therefore, noise does not occur in the current control element drive signal c.

In addition, the wiring inductors of the snubber circuits 21 to 23 are
To reduce the inductance L, the capacitor C_S1And die
Aether D_S1Connection part and resistance R_S1Conductor L between_S1, Con
Densa C_S2And diode D_S2Connection part and resistance R_S2of
Conductor L between_S2, Capacitor C _S3And diode D_S3The conclusion
Line part and resistance R_S3Conductor L between_S3, Capacitor C_S4as well as
Diode D_S4Connection part and resistance R_S4Conductor L between_S4,
Capacitor C_S5And diode D_S5Connection part and resistance R
_S5Conductor L between_S5, And capacitor C_S6And diode
D_S6Connection part and resistance R_S6Conductor L between_S6Is width
It is made of wide, short trapezoidal plates.

In this way, the snubber circuits 21 to 23 are
Can be fully functional. In addition, in FIGS.
As shown, the first, second and third insulating materials 33, 34, 35
One end of the flat board fixed to the other board not shown.
Sliding capacitor C₁, C ₂A pair of notches to support the
63 and 64 are formed, and a smoothing capacitor C₁，
C₂Penetrates the notches 63 and 64 and is perpendicular to the substrate 61
Fixed to. In addition, 65 is the smoothing capacitor
C₁, C₂Discharge resistance to discharge the electric charge remaining in the
Anti, C is a power transistor Tr₁~ Tr₆Collect
E and E are power transistors Tr₁~ Tr₆The emitter of
Is.

Next, the power transistors Tr _{1 to} Tr ₆
The heat dissipation device will be described. In FIGS. 13 to 15, reference numeral 53 is a frame of a heat dissipation device arranged adjacent to each other, and a cooling block 56 for absorbing heat is erected on each frame 53, and one side is provided on one side of the cooling block 56. The elements for the inverter bridge 18 (FIG. 1) of the motor 11 (FIG. 2) are arranged, and the elements for the inverter bridge 18 of the other motor are arranged on the other side.

That is, the power transistors Tr ₁ and Tr ₂ for the inverter bridge 18 of the one motor 11 are vertically mounted so as to come into contact with one surface of the cooling block 56, and the other surface of the cooling block 56 is mounted on the other surface. The power transistors Tr ₁ and Tr ₂ for the inverter bridge 18 of the other motor are vertically attached so as to be in contact with each other (note that since the power transistor Tr ₂ is located below the power transistor Tr ₁ in FIG. Not shown.).

Further, the power transistors Tr ₃ and Tr ₄ are vertically attached to another cooling block (not shown),
Power transistors Tr ₅ and T ₅ are provided in the other cooling blocks.
r ₆ is mounted up and down. The power transistors Tr _{1 to} Tr ₆ generate heat when turned on and a large current flows. Therefore, the power transistors Tr _{1 to} T
The heat generated by r ₆ is transferred to the cooling block 56 and radiated into the air.

Therefore, in each of the cooling blocks 56, a plurality of tubes for flowing a cooling medium, for example, a heat pipe 60 composed of a heat absorbing portion and a heat radiating portion in this embodiment.
Is embedded, one end of the heat pipe 60 is projected into the air, press-fitted into several fins so as to increase the heat radiation area, and fixed by an adhesive. Then, a fan (not shown) is provided corresponding to the cooling block 56, and cold air can be supplied to the heat pipe 60 by operating the fan. The fan is arranged above the cooling block 56 so as to face the heat dissipation portion of the heat pipe 60.

Therefore, the power transistor Tr
_The heat generated by _{1 to} Tr ₆ is transferred to the cooling block 56, further transferred to the heat pipe 60, and radiated into the air by the cool air of the fan. Then, the cooling block 56 and the power transistor Tr ₁ to Tr ₆ so as to sandwich from both sides, at least a pair of substrates 61 vertically, is secured by bolts (not shown) to the power transistor Tr ₁ to Tr _6.

The present invention is not limited to the above embodiments, but various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a plan view of a motor control device for an electric vehicle showing an embodiment of the present invention.

FIG. 2 is a block diagram of a motor control device for an electric vehicle showing an embodiment of the present invention.

FIG. 3 is a circuit diagram of an inverter bridge in the embodiment of the present invention.

FIG. 4 is a front view of a motor control device for an electric vehicle showing an embodiment of the present invention.

5 is a cross-sectional view taken along the line AA of FIG.

6 is a sectional view taken along line BB of FIG.

FIG. 7 is a diagram showing a positive electrode bus according to an example of the present invention.

FIG. 8 is a diagram showing a negative electrode bus according to an example of the present invention.

FIG. 9 is a diagram showing a first insulating material in the example of the present invention.

FIG. 10 is a diagram showing a second insulating material in the example of the present invention.

FIG. 11 is a diagram showing a third insulating material in the example of the present invention.

FIG. 12 is a mounting state diagram of a smoothing capacitor in an example of the present invention.

FIG. 13 is a mounting state diagram of the power transistor in the example of the present invention.

FIG. 14 is a side view of a heat dissipation device for a power transistor according to an embodiment of the present invention.

FIG. 15 is a front view of a heat dissipation device for a power transistor according to an example of the present invention.

[Explanation of symbols]

21-23 Snubber circuit 31 Positive bus 32 Negative bus 61 Substrate Δv Surge voltage C _{S1 to} C _S6 Capacitors D _{1 to} D ₆ , D _{S1 to} D _S6 Diodes L _{S1 to} L _S6 Conductor R _{S1 to} R _S6 Resistance Tr _{1 to} Tr ₆ power transistors

Claims (1)

[Claims] 1. A substrate comprising: (a) a plate-shaped positive electrode bus and a plate-shaped negative electrode bus extending in parallel with the positive electrode bus; and (b) electrically connecting the positive electrode bus and the negative electrode bus for selection. A plurality of pairs of current control elements that switch dynamically, and (c) a snubber circuit that is connected to each pair of current control elements on the substrate and that absorbs a surge voltage generated during a switching operation of the current control elements. d) The snubber circuit is composed of a capacitor, a diode and a resistor, and (e) each element of the snubber circuit is connected by a plate-shaped conductor.