JP2000312488A - Inverter device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide with a simple circuit configuration a double power source type inverter device which can easily increase the operating speed of an inverter circuit. SOLUTION: An inverter device supplies high-voltage power from a high- voltage battery 2 to a running motor through an inverer circuit 10. Control signals, outputted from a control circuit 12 for controlling inverter, are respectively impressed upon the control electrodes of switching elements 14a-14f of the inverter circuit 10, after the signals are converted into control voltages of potential levels make appropriate for the elements 14a-14f through driver circuits 16a-16f. The lower-order output terminal of a DC stepdown circuit 11, which receives electric power from the battery 2 and supplies power supply voltages to the control circuit 12, and driver circuits 16a-16f is connected to the lower-order power supply terminal of the battery 2, and at the same time, to the lower-order power supply terminals of the driver circuits 16d, 16e, and 16f and the lower-order power supply terminal of the control circuit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle inverter device mounted on an electric vehicle or a hybrid vehicle.

[0002]

2. Description of the Related Art A durable AC motor including a traveling motor, for example, a brushless DC motor is used in an electric circuit of a conventional electric vehicle or hybrid vehicle, and an inverter circuit is used for controlling the motor. The battery for supplying power to the traveling motor is separated from the low-voltage battery for supplying power to other devices, and employs a battery having a higher voltage than the low-voltage battery. As a result, the current flowing through the motor and the inverter circuit for controlling the motor is reduced, so that the size of the switching element of the inverter circuit, the weight of the motor-system wiring cable, and the power loss thereof are reduced.

[0003] However, power consumption does not matter and there is no advantage of the above-mentioned high voltage, for example, an accelerator signal or a brake signal is taken in, and a torque required as a vehicle is calculated.
A traveling ECU that transmits the torque command value to the inverter
An air-conditioning ECU that drives / stops the fan using the temperature in the passenger compartment and the panel operation of the passenger as inputs, and calculates the required number of revolutions of the electric compressor from them and sends the revolution number command value to the inverter. For example, power was supplied directly from existing low-voltage batteries.

Further, in addition to the above-mentioned reasons, a control circuit (controller) attached to the inverter and for controlling the inverter circuit is also used in consideration of the advantage that an interface with each ECU can be easily configured. Power was supplied directly.

[0005]

However, in the above-mentioned conventional electric vehicle having a dual power supply configuration, a photocoupler is usually provided between the control circuit for controlling the inverter and the control electrode of each switching element of the inverter circuit. However, there is a problem that the input / output insulation type buffer circuit is required and the circuit configuration becomes complicated.

Further, when a photocoupler is used, it is not easy to speed up the driving of a high power switching element because the output current of the light receiving element is small, so that power loss of the inverter circuit and heat generation due to the power loss are generated. There was a problem of being big. More specifically, in the inverter circuit, the power loss of the switching element is reduced.
Although it is an important issue in terms of increasing the size of the switching element and cooling it, most of the power loss (the product of the resistance and the square of the current) of the switching element that operates intermittently is higher than the on-state loss after full on. It is already known that the transient loss from ON to OFF and from OFF to ON (transient) is large. This is due to the fact that the current is relatively small but the resistance is large in the transient state. If the switching frequency is increased for high-speed control of the traveling motor, there is a problem that the transient loss is further increased.

[0007] In addition, in order to control a motor, a current or voltage detected from a high-voltage battery or a motor is input to an inverter control circuit for controlling a motor control inverter circuit. There is a problem that an input / output isolation type buffer circuit such as a coupler is required, and the circuit configuration is complicated. The present invention has been made in view of the above problems, and an object of the present invention is to provide a dual power supply type vehicle inverter device that can easily increase the speed of an inverter circuit with a simple circuit configuration. I have.

[0008]

According to the first aspect of the present invention, a high-voltage power is supplied from a high-voltage battery to a traveling motor through an inverter circuit. The control signal output from the control circuit for inverter control is:
The voltage is converted into a control voltage of an appropriate potential level for each switching element through a driver circuit (buffer circuit), and applied to the control electrode of each switching element of the inverter circuit.

The high-voltage battery mentioned here means a battery which is electrically insulated from a low-voltage battery whose lower power supply terminal is grounded to the vehicle body and generates a higher voltage than the low-voltage battery. In this configuration, in particular, the lower output terminal of the DC step-down circuit that is supplied with power from the high-voltage battery and supplies the power supply voltage to the control circuit and the driver circuit for inverter control is connected to the lower power terminal of the high-voltage battery directly or through a current detection resistor, Further, the lower power supply terminal of the driver circuit for controlling the low-side switching element of the common source type or the common emitter type is directly connected to the lower output terminal of the DC step-down circuit.

In other words, according to this configuration, the lower power supply terminal of the high voltage battery is connected directly or through a current detection resistor to the lower power supply terminal of the driver circuit for controlling the low-side switching element of the common source type or the common emitter type, and The driver circuit is connected to both of the lower power supply terminals of a control circuit for controlling the inverter that outputs a control signal. With this configuration, it is not necessary to provide an input / output insulated buffer circuit such as a photocoupler in a driver circuit for intermittently controlling the low-side switching element of the inverter circuit. Since the power element in the subsequent stage can be operated at high speed because it is not used, the switching element of the inverter circuit can also be switched on and off at a high speed, so that the effect of reducing the switching loss, particularly the large power loss during the switching transition period, can be achieved. it can.

In addition, a current detecting resistor is provided between a lower power supply terminal of the inverter circuit and a lower power supply terminal of the high voltage battery,
The voltage at both ends, which is proportional to the current, can be directly input to the control circuit for inverter control without passing through the input / output insulated buffer circuit, and the circuit configuration can be further simplified. it can. According to the configuration of the second or fourth aspect, the control circuit for inverter control detects the voltage of the high-voltage battery in a non-insulated manner, and performs a different control operation when the voltage deviates from the predetermined range than when no deviation occurs. To the three-phase inverter circuit.

With this configuration, the control circuit for controlling the inverter can directly detect the battery voltage without passing through the input / output insulated buffer circuit. The operation of the circuit can be set to an emergency mode different from the normal mode. It should be noted that abnormal battery voltage means, for example, when the voltage is too high or too low, and emergency mode means, for example, stopping the inverter circuit. With this configuration, it is possible to prevent an excessive voltage from being applied to the inverter circuit, resulting in an excessively large current, thereby preventing overheating of the inverter circuit from becoming a problem, and preventing deterioration of the high-voltage battery due to overdischarge. .

According to the third or fifth aspect, the control circuit for controlling the inverter can detect the AC voltage applied to the AC motor in a non-insulated manner and form a control signal based on the AC voltage. Therefore, the input / output insulated buffer circuit is not required, and the traveling motor can be precisely controlled with a simple configuration.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the following examples.

[0015]

Embodiment 1 An embodiment of a vehicle inverter device according to the present invention will be described with reference to a block circuit shown in FIG. (Overall Configuration) In FIG. 1, 1 is a vehicle inverter device, 2 is a high-voltage battery, 3 is a low-voltage battery, 4 is a traveling motor composed of a three-phase brushless DC motor, 5 is an ECU,
6 is a connector.

The vehicle inverter device 1 includes an inverter circuit 10, a DC step-down circuit 11, a controller (control circuit for controlling the inverter circuit) 12, a photocoupler 13a,
3b, a driver circuit 16, a current detection resistor 20 for detecting a part of the motor current, and a smoothing capacitor 21 for smoothing the input voltage from the high voltage battery 2. Driver circuit 16
Is the driver circuit 16 on the high side (upper arm side)
a, 16b, and 16c, and low-side (lower-arm) driver circuits 16d, 16e, and 16f.

The ECU 5 is supplied with electric power from a low-voltage battery 3 whose lower power supply terminal is grounded to the vehicle body, and outputs a motor control command signal for controlling the traveling motor 4 based on at least an accelerator pedal depression amount and a brake pedal depression amount. Transmit to the device 1. Hereinafter, each part of the vehicle inverter device 1 will be described in more detail. (Inverter Circuit 10) The inverter circuit 10 is an NPN
This is a three-phase inverter circuit composed of IGBTs 14a to 14f of the type and diodes 15a to 15f individually and connected in anti-parallel with each other. Since it has a well-known circuit configuration, further detailed description is omitted. However, in this embodiment, the IGBTs 14a, 1
4b and 14c are emitter-follower connections (connection of a collector grounding type), and the collector terminals thereof are connected to the high voltage battery 2
Is connected to the higher power supply terminal 2a. In addition, IGBTs 14d, 14e, 1
4f is a grounded emitter connection, and its emitter terminal is connected to the low power supply terminal 2b of the high voltage battery 2 through the low resistance current detection resistor 20.

Reference numeral 17 denotes a U-phase output terminal of the inverter circuit 10 connected to the U-phase terminal of the traveling motor 4, and reference numeral 18 denotes a V-phase output terminal of the inverter circuit 10 connected to the V-phase terminal of the traveling motor 4. , 19 are W-phase output terminals of the inverter circuit 10 connected to the W-phase terminal of the traveling motor 4. (DC Step-Down Circuit 11) The circuit configuration of the DC step-down circuit 11 will be described with reference to FIG.

The DC step-down circuit 11 is a step-down DC-DC converter, and includes a transformer 11a, a rectifier circuit 11b,
It has a well-known configuration including 11c, 11d, 11e and a switching circuit (single-phase inverter circuit) 11f.
The transformer 11a has one primary coil and four secondary coils, and has a turns ratio for realizing a predetermined step-down ratio. The rectifier circuits 11b, 11c, 11d, and 11e are the simplest half-wave rectifier circuits including the diode D and the capacitor C, but may be changed to more complicated rectifier circuits. The switching circuit 11f includes an oscillation circuit 11g having a variable duty ratio that oscillates at a constant frequency or a variable frequency, and an output transistor 11h that amplifies the rectangular wave voltage output from the oscillation circuit 11g. The oscillation circuit 11g has a built-in output voltage control circuit, and the output voltage control circuit receives a reference voltage and the output voltage of the rectifier circuit 11e. The output voltage control circuit operates when the output voltage is higher than the reference voltage. The duty ratio of the oscillation circuit 11g is increased when the output voltage is lower than the reference voltage. Thus, the output voltage of the rectifier circuit 11e can be made constant regardless of the voltage fluctuation of the high voltage battery 2.

The high output terminal of the rectifier circuit 11b is connected to the high power terminal of the driver circuit 16a on the high side, and the low output terminal of the rectifier circuit 11b is connected to the low power terminal and the U-phase output terminal of the driver circuit 16a. . In other words, the driver circuit 16a is supplied with a power supply voltage having the emitter potential of the switching element 14a as a reference potential (lower power supply terminal potential). This is because the control voltage of the switching element 14a is formed based on the emitter (so-called emitter follower operation).

The higher output terminal of the rectifier circuit 11c is connected to the higher power supply terminal of the driver circuit 16b on the high side, and the lower output terminal of the rectifier circuit 11c is connected to the lower power supply terminal and the V-phase output terminal of the driver circuit 16b. . That is, a power supply voltage having the emitter potential of the switching element 14b as a reference potential (lower power supply terminal potential) is applied to the driver circuit 16b. This is because the control voltage of the switching element 14b is formed based on the emitter (so-called emitter follower operation).

The high output terminal of the rectifier circuit 11d is connected to the high power terminal of the driver circuit 16c on the high side, and the low output terminal of the rectifier circuit 11d is connected to the low power terminal and the W-phase output terminal of the driver circuit 16c. . That is, a power supply voltage with the emitter potential of the switching element 14c as a reference potential (lower power supply terminal potential) is applied to the driver circuit 16c. This is because the control voltage of the switching element 14c is formed based on the emitter (so-called emitter follower operation).

The higher output terminal of the rectifier circuit 11e is connected to the higher power supply terminals of the driver circuits 16d, 16e and 16f on the low side, and the lower output terminal of the rectifier circuit 11e is connected to the lower power supply terminals of the driver circuits 16d, 16e and 16f. The switching circuit 11 f is connected to the lower power supply terminal and connected to the lower power supply terminal of the high voltage battery 2 through the current detection resistor 20.

That is, the driver circuits 16d, 16e,
In 16f, switching elements 14d, 14e, 14f
Is applied as a reference potential (lower power supply terminal potential). This is the switching element 14
This is because the control voltages d, 14e, and 14f are formed based on the emitter (so-called emitter grounding operation). In addition, the high output terminal and the low output terminal of the rectifier circuit 11e are connected to the high power terminal and the low power terminal of the controller 12,
Supply power to the controller.

(Controller 12) The controller 12 is a control circuit having a general microcomputer configuration, and includes a motor control command from the ECU 5 input through the photocoupler circuit 13b, a voltage of the high-voltage battery 2 input through the cable 200, and a cable 201. , 202, and the three-phase AC output voltage of the inverter circuit 10 inputted through the cables 203 to 205, the driver circuits 16a, 16b, 16c,.
Control signals are output to 16d, 16e and 16f. Also,
The operation state is output to the ECU 5 through the photocoupler 13a.

(Driver circuits 16a, 16b, 16c)
FIG. 3 shows an example of the driver circuit 16a. Reference numeral 161 denotes a photocoupler circuit; 162, a load resistance of a phototransistor in the photocoupler circuit 161; 163, a complementary emitter follower circuit for current-amplifying the output voltage of the photocoupler circuit 161;

The switching element 14a control signal output from the controller 12 is converted into a control voltage based on the emitter potential of the switching element 14a by this driver circuit 16a, amplified and applied to the gate electrode of the switching element 14a without any problem. Switching element 14d,
14e and 14f can be controlled. Since the driver circuits 16b and 16c are the same, the description is omitted.

(Driver circuits 16d, 16e, 16f)
FIG. 4 shows an example of the driver circuit 16d. 171 is PN
P emitter grounded transistor, 172 is transistor 1
Reference numeral 173 denotes a complementary emitter follower circuit for amplifying the current of the output voltage of the transistor 171, and reference numeral 174 denotes a current limiting resistance of the complementary emitter follower circuit 163.

This driver circuit 16d is the driver circuit 1
A difference is that the photocoupler circuit 161 of FIG. 6a is replaced with a transistor 171.
f has the same circuit configuration. However, the lower power supply terminals of the driver circuits 16a, 16b, 16c are connected to the rectifier circuit 11e.
Of the driver circuits 16a and 16
b, 16c are connected to the higher output terminals of the rectifier circuit 11e, and as a result, the driver circuits 16d, 16e,
The lower power supply terminal of 16f is the low-side switching element 1
It is characterized in that it is connected to the emitter terminals of 4d, 14e and 14f.

With this configuration, the switching elements 14d and 14 output from the controller 12 are provided.
e, 14f control signals are supplied to the driver circuits 16d, 16e, 1
At 6f, the control voltage is converted into a control voltage based on the emitter potentials of the switching elements 14d, 14e, 14f, amplified and applied to the gate electrodes of the switching elements 14d, 14e, 14f.
4f can be controlled.

As the DC step-down circuit 11, in addition to the above-described transformer / rectifier circuit configuration, various known DC types such as a switched capacitor type and a charge pump type can be used.
Naturally, a DC converter can be adopted. (Control Operation of Controller 12) The inverter circuit control operation of the controller 12 will be described with reference to the flowchart shown in FIG.

The controller 12 reads the voltage of the high-voltage battery 2 (s100). If the voltage is within a predetermined range stored in advance, the controller 12 sets the EC in step s104.
A motor command is read from U5, and vector control is performed on the traveling motor 4 based on the read motor command, motor voltage (three-phase AC voltage), and motor current to generate a torque value corresponding to the motor command. On the other hand, if the voltage of the high-voltage battery 2 is out of the above range in step s104, the inverter circuit 10 is turned off (s103).
(Effect) By adopting the above circuit configuration, the above-described operation and effect of the present invention can be obtained. In particular, it is not necessary to provide input / output insulation in the low-side driver circuits 16d, 16e, and 16f, which is expensive and requires high power. It is possible to obtain an advantage that a photocoupler that is small and makes it difficult to operate the subsequent power element at high speed can be omitted.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a vehicle inverter device of the present invention.

FIG. 2 is a circuit diagram of the DC step-down circuit of FIG.

FIG. 3 is a circuit diagram showing a high-side driver circuit of FIG. 1;

FIG. 4 is a circuit diagram showing a low-side driver circuit of FIG. 1;

FIG. 5 is a control circuit (controller) for inverter control.
6 is a flowchart showing the motor control operation of FIG.

[Explanation of symbols]

1 is a vehicle inverter device, 2 is a high voltage battery, 3 is a low voltage battery, 4 is a motor, 10 is an inverter circuit, 11
Is a DC step-down circuit, 12 is a controller (control circuit for controlling the inverter), 14a, 14b, 14c, 14d, 1
4e, 14f are switching elements, 16a, 16b, 1
6c, 16d, 16e, 16f are driver circuits

Continued on the front page F term (reference) 5H007 AA04 BB06 CA01 CB05 CC23 DB07 DC02 DC05 5H115 PC06 PG04 PI16 PI21 PI29 PI30 PU11 PU21 PV03 PV09 PV23 QA10 QN03 RB26 SE03 TO12 TO13 TO22 TO24 TR19 TU05 TU06 TZ04 5H560 AA13 EB12 DC GG04 JJ03 RR10 SS02 SS04 TT18 UA06 XA13

Claims (5)

[Claims] 1. An inverter circuit configured by a bridge connection of a plurality of high-side switching elements and a low-side switching element, converts DC power supplied from a high-voltage battery into AC power, and supplies the AC power to an AC motor. A driver circuit for applying a control voltage to a control electrode of each switching element of the three-phase inverter circuit in accordance with a control signal to intermittently control the switching elements; and a control for inverter control for outputting the control signal to the driver circuit. Circuit, comprising: a DC step-down circuit that is supplied with power from the high-voltage battery and supplies power to the driver circuit and the control circuit for controlling the inverter, and a low-level output terminal of the DC step-down circuit, A direct or current detection resistor is connected to the lower power supply end of the high voltage battery. The driver circuit for controlling the low-side switching element comprises an input / output non-insulated amplifier circuit that outputs a control voltage to a control electrode of the low-side switching element of a source (emitter) grounded type, A low-voltage power supply terminal of the driver circuit for controlling the low-side switching element is directly connected to a low-voltage output terminal of the DC step-down circuit. 2. The vehicle inverter device according to claim 1, wherein the control circuit for inverter control detects the voltage of the high-voltage battery in a non-insulated manner, and when the voltage deviates from a predetermined range, the deviation is determined. An inverter device for a vehicle, wherein the control signal for instructing a control operation different from a case in which the control operation does not occur is output to the driver circuit. 3. The vehicle inverter device according to claim 1, wherein the control circuit for controlling the inverter detects an AC voltage applied to the traveling motor in a non-insulated manner, and performs the detection based on the AC voltage. An inverter device for a vehicle, which forms a control signal. 4. An inverter circuit configured by a bridge connection of a plurality of high-side switching elements and a low-side switching element to convert DC power supplied from a high-voltage battery into AC power and supply the AC power to an AC motor. A driver circuit for applying a control voltage to a control electrode of each switching element of the inverter circuit in accordance with a control signal to intermittently control the switching elements, and a control circuit for inverter control for outputting the control signal to the driver circuit; An inverter device for a vehicle, comprising: a DC step-down circuit that is supplied with power from the high-voltage battery and supplies power to the driver circuit and the control circuit for controlling the inverter, and a low-level output terminal of the DC step-down circuit includes the high-voltage output terminal. Directly to the lower power supply end of the battery or through a current sensing resistor The control circuit for controlling the inverter is configured to detect the voltage of the high-voltage battery in a non-insulated manner, and to instruct a control operation different from a case where the deviation does not occur when the voltage deviates from a predetermined range. A vehicle inverter device for outputting the control signal to the driver circuit. 5. The inverter device for a vehicle according to claim 4, wherein the control circuit for controlling the inverter detects an AC voltage applied to the AC motor in a non-insulated manner, and controls the control signal based on the AC voltage. A vehicle inverter device characterized by forming: