JP2017005824A - Inverter drive circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize an inverter drive circuit.SOLUTION: The inverter drive circuit for driving an inverter circuit includes a control unit 8 and a selection unit 7a (7b) which selects predetermined temperature information between the temperature information of switch elements Qu1 and Qd1 disposed on the upper arm and the lower arm of the inverter circuit, to transmit the selected temperature information to the control unit 8.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inverter drive circuit.

  Some inverter drive circuits have a function of performing a protection operation from temperature information such as a switch element. When the temperature information related to the temperature of the switch element used for the upper arm and lower arm of the inverter circuit is transmitted to the control unit mounted on the inverter drive circuit, the number of input ports (terminals) of the control unit is limited. Therefore, an input port may not be prepared for all the temperature information of each switch element. For example, in the case of a three-phase inverter circuit, since there are six switch elements including the upper and lower arms, it is necessary to prepare six input ports that can receive temperature information. Even if the same number of input ports as the temperature information can be prepared in the control unit, there is a problem that the inverter drive circuit becomes larger due to the increase of the input ports. Furthermore, since the control unit that has received all the temperature information has to process each piece of temperature information, the processing load on the control unit increases. Refer to Patent Document 1 for related technology. In addition, some integrated circuits used in the drive unit for driving the switch element are provided with input / output ports (terminals) for each function, and there is a problem that the inverter drive circuit becomes large.

JP 2005-168262 A

  An object of one aspect of the present invention is to reduce the size of an inverter drive circuit.

The inverter drive circuit which is one form which concerns on this invention is provided with a control part and a selection part.
The control unit is provided in an inverter drive circuit that drives the inverter circuit.
The selection unit selects predetermined temperature information from the temperature information of the switch elements provided in the upper arm and the lower arm of the inverter circuit, and transmits the selected predetermined temperature information to the control unit.

The selection unit is provided for each phase of the inverter circuit, and selects temperature information of the switch elements of the upper arm and the lower arm for each phase.
An inverter drive circuit according to one aspect of the present invention includes a drive switch element that drives a switch element, a pause switch element that pauses the switch element, an output terminal of the drive switch element, and a control terminal of the switch element, A driving resistor connected between, a pause resistor connected between the output terminal of the pause switch element and the control terminal of the switch element, a pause holding switch element that holds the pause state of the switch element, A control voltage detector.

  The control voltage detection unit detects the voltage at the output terminal of the drive switch element connected to the drive resistor, and controls the drive and pause of the pause holding switch element according to the detected voltage.

  The inverter drive circuit can be reduced in size.

It is a figure which shows one Example of an inverter drive circuit. It is a figure which shows another Example of an inverter drive circuit. It is a figure which shows one Example of the drive circuit which an inverter drive circuit has.

Hereinafter, embodiments will be described in detail with reference to the drawings.
<Embodiment>
FIG. 1 is a diagram illustrating an embodiment of an inverter drive circuit. The inverter circuit shown in FIG. 1 includes an upper arm switch element Qu1 and a lower arm switch element Qd1. The switch element Qu1 is driven by the drive unit 6a, and the switch element Qd1 is driven by the drive unit 6b. For example, IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) may be used as the switch elements Qu1 and Qd1. In the example of FIG. 1, only one upper and lower arm is shown for convenience, but in the case of a three-phase inverter circuit, upper and lower arms are provided for each of the U phase, V phase, and W phase.

  The upper arm circuit shown in FIG. 1 includes a low voltage circuit 1a, a high voltage circuit 2a, an insulating unit 3a, a temperature detecting unit 4a, and a temperature measuring unit 5a. The lower arm circuit shown in FIG. 1 includes the low voltage circuit 1b and the high voltage circuit 2b. , An insulating part 3b, a temperature detecting part 4b, a temperature measuring part 5b, and a selecting part 7a. In the example of FIG. 1, only the circuits related to the upper arm switch element Qu1 and the lower arm switch element Qd1 are shown. Is provided with a switch element. Therefore, in the case of a three-phase inverter circuit, six of the above circuits are provided for six switch elements.

The low-voltage circuits 1a and 1b are circuits that are driven at a low voltage, and include, for example, a circuit that transmits a signal to the input port of the control unit 8.
The high-voltage circuits 2a and 2b are circuits driven at a high voltage, and include, for example, a circuit connected to an inverter circuit. The insulating unit 3a and the insulating unit 3b are a circuit that insulates the low voltage circuit 1a from the high voltage circuit 2a and a circuit that insulates the low voltage circuit 1b from the high voltage circuit 2b. In FIG. 1, the driving units 6a and 6b are not included in the high-voltage circuits 2a and 2b. However, the driving unit 6a may be provided in the high-voltage circuit 2a, and the driving unit 6b may be provided in the high-voltage circuit 2b.

  The temperature detection unit 4a receives the value measured by the temperature measurement unit 5a through the terminal p2 of the high voltage circuit 2a, generates temperature information based on the received value, and generates the generated temperature information through the insulation unit 3a. And output to the low voltage circuit 1a. The temperature detection unit 4b receives the value measured by the temperature measurement unit 5b via the terminal p5 of the high-voltage circuit 2b, generates temperature information based on the received value, and transmits the generated temperature information to the insulating unit 3b. To the low-voltage circuit 1b. The temperature measuring units 5a and 5b measure the temperatures related to the switch elements Qu1 and Qd1, respectively, directly or indirectly. For example, the temperature measuring units 5a and 5b are also measurement circuits that measure the forward voltage of the diodes connected to the switch elements Qu1 and Qd1. Alternatively, a thermistor or a thermocouple may be used.

  The selector 7a is provided in the low voltage circuit 1a or 1b. In the example of FIG. 1, it is provided in the low voltage circuit 1b. The selection unit 7a includes an input terminal that receives temperature information transmitted from the temperature detection unit 4a and an input terminal that receives temperature information transmitted from the temperature detection unit 4b. The temperature information transmitted from the temperature detection unit 4a is received by the selection unit 7a via a wiring connecting the terminal p1 of the low voltage circuit 1a and the terminal p3 of the low voltage circuit 1b. The temperature information transmitted from the temperature detection unit 4b is received by the selection unit 7a via the insulating unit 3b.

  Subsequently, when the selection unit 7a receives the temperature information from the temperature detection unit 4a and the temperature detection unit 4b, the selection unit 7a selects the temperature information indicating the high temperature (temperature information on the higher temperature), and the terminal p4 of the low-voltage circuit 1b. The temperature information indicating the selected high temperature is transmitted to the control unit 8 via. That is, the processing that has been executed by the control unit 8 in the prior art can be allocated to the selection unit 7a.

  The control unit 8 is a circuit that is provided in the inverter drive circuit and controls the inverter drive circuit. For example, it is configured using a CPU (Central Processing Unit), a multi-core CPU, a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), or the like).

  In the example of FIG. 1, the selection unit 7a is provided with a pair of upper and lower arms, because the same current flows through the switch elements Qu1 and Qd1 of the upper and lower arms of the same phase. Therefore, in the case of a three-phase inverter circuit, it is desirable to provide a selector 7a for each upper and lower arm of the U phase, V phase, and W phase. That is, it is desirable to provide the selection unit 7a for each phase.

  By providing the selection unit 7a as described above, the number of input ports previously provided in the control unit 8 as many as the number of switch elements can be reduced as compared with the conventional case, so that the inverter drive circuit can be made smaller. Can do. For example, in the case of an inverter drive circuit of a three-phase inverter circuit, six input ports are conventionally required, but in the embodiment, only three input ports need be prepared in the control unit 8.

Furthermore, since the processing that has been executed by the control unit 8 can be distributed to the selection unit 7a, the processing load on the control unit 8 can be reduced.
In the embodiment, the selection unit 7a is provided with a pair of upper and lower arms, but the following method may be used.
(1) A method of providing one selection unit 7a for all switch elements. For example, in the case of a three-phase inverter circuit, one selection unit 7a is provided for six switch elements of the upper and lower arms of the U phase, V phase, and W phase. In this case, the number of inputs to the selection unit 7a is six, temperature information indicating the highest temperature is selected from the six, and the selected temperature information is transmitted. Therefore, the control unit 8 prepares one input port.
(2) A method of providing one selection unit 7a for all the switch elements of the upper arm and one selection unit 7a for all the switch elements of the lower arm. For example, in the case of a three-phase inverter circuit, one selection unit 7a for each of the upper arm switch elements for the U phase, V phase, and W phase, and the lower arm switch element for each of the U phase, V phase, and W phase. One selection unit 7a is provided for three units. In this case, there are three inputs to the selection unit 7a of the upper arm, temperature information indicating the highest temperature is selected from the three, and the selected temperature information is transmitted. Also, there are three inputs to the lower arm selector 7a, and temperature information indicating the highest temperature is selected from the three, and the selected temperature information is transmitted. Therefore, the control unit 8 prepares two input ports.

A modification of the embodiment will be described.
FIG. 2 is a diagram showing another embodiment of the inverter drive circuit. The difference between the inverter circuit shown in FIG. 2 and the inverter drive circuit described in the embodiment of FIG. 1 is the selection unit 7b and the control unit 8 in FIG.

  2 receives the switching signal transmitted from the control unit 8 via the terminal p6 of the low-voltage circuit 1b, selects temperature information based on the switching signal, and sends the selected temperature information to the control unit 8. Send. That is, while only the temperature information indicating the high temperature is selected in the embodiment of FIG. 1, not only the temperature information indicating the high temperature but also other temperature information can be transmitted to the control unit 8 in the modified example.

  The control unit 8 in FIG. 2 generates a switching signal for selecting one from a plurality of temperature information, and outputs it to the selection unit 7b. Upon receiving the switching signal, the selection unit 7b selects temperature information based on the switching signal. Here, the switching signal includes information for selecting any one of the plurality of temperature information. In the example of FIG. 2, information for selecting either the temperature information of the upper arm switch element Qu1 or the temperature information of the lower arm switch element Qd1 is included. Subsequently, the selected temperature information is transmitted from the selection unit 7b, and the control unit 8 receives the selected temperature information.

  By providing the selection unit 7b as described above, the processing load on the control unit 8 can be reduced by using fewer input ports than in the past. For example, in the case of an inverter drive circuit of a three-phase inverter circuit, six input ports are conventionally required, but in the modified example, only three input ports and one output port need be prepared in the control unit 8, The inverter drive circuit can be reduced in size.

Moreover, since not only the temperature information indicating high temperature but also other temperature information can be received, the control of the inverter drive circuit can be further improved.
Next, the drive unit 6a (6b) will be described.

  FIG. 3 is a diagram illustrating an example of a drive unit included in the inverter drive circuit. The drive unit 6a shown in FIG. 3 includes a gate drive unit that controls driving (on / off control) of the switching element Qu1 and a control voltage detection unit 304 (one-dot chain line) that detects the voltage of the control terminal. The integrated circuit 301 and a prevention unit that prevents malfunction of the switch element Qu1 are included.

  When an input / output port is provided in an integrated circuit for each function, if a control voltage detection unit 304 and a prevention unit are provided, a wiring 300 (broken line), a resistor R1, an input terminal p12, etc. as shown in FIG. Therefore, the drive part 6a will become large. Therefore, in the drive unit 6a illustrated in FIG. 3, the wiring 300 (broken line) and the resistor R1 are moved into the integrated circuit 301, and the input terminal p12 illustrated in FIG. 3 is used as the integrated circuit 301 as the wiring 303 and the resistor R1 illustrated in FIG. Eliminate. As a result, each of the drive units 6a and 6b in FIGS. 1 and 2 can be reduced in size, so that the inverter drive circuit can also be reduced in size.

The gate driving unit will be described.
The gate drive unit includes a logic circuit 302, a drive switch element S1, a pause switch element S2, a capacitor C1, resistors R1 to R4, and the like. The logic circuit 302 receives a control signal (for example, a PWM (Pulse Width Modulation) signal) transmitted from the control unit 8 via the terminal p7, and based on the control signal, the driving switch element S1 and the suspension switch element S2 A signal for controlling (on / off control) driving and pause is generated and output.

  The drive switch element S1 outputs a signal for driving the switch element Qu1. The control terminal (gate) of the drive switch element S1 is connected to the drive output terminal of the logic circuit 302, and one terminal (source) of the drive switch element S1 is connected to the power supply VCC via the power supply terminal p8. The other terminal (drain) of the drive switch element S1 is connected to the output terminal p9. The driving resistors R2 and R3 are connected between the other terminal of the driving switch element S1 and the control terminal (gate) of the switch element Qu1.

  The suspension switch element S2 outputs a signal for suspending the switch element Qu1. The control terminal (gate) of the pause switch element S2 is connected to the pause output terminal of the logic circuit 302, and one terminal (drain) of the pause switch element S2 is connected to the output terminal p10. The other terminal (source) of the suspension switch element S2 is connected to the ground via the ground terminal p11. The pause resistors R4 and R3 are connected between one terminal of the pause switch element S2 and the control terminal of the switch element Qu1.

  In the drive unit 6a shown in FIG. 3, the output terminal p9 connected to the other terminal of the drive switch element S1 and the output terminal p10 connected to one terminal of the pause switch element S2 are separately provided. Is provided. Therefore, the output terminal p9 is in an indefinite state (open) when the driving switch element S1 is in the inactive state, and the output terminal p10 is in an indefinite state (open) when the inactive switch element S2 is in the inactive state. Therefore, when the drive switch element S1 is in the resting state, a change similar to the voltage at the control terminal of the switch element Qu1 can be measured at the output terminal p9. In other words, by connecting the wiring 303 to the output terminal p9 of the driving switch element S1 instead of the output terminal p10 of the suspension switch element S2, the switch element Qu1 and the resistance and capacitance of the peripheral circuit at the time of transition to the suspension gradually. It is possible to measure changes that change to approach the ground voltage. Further, it is conceivable to use MOSFETs, IGBTs or the like as the drive switch element S1 and the suspension switch element S2.

  The control voltage detection unit 304 detects the voltage of the control terminal of the switch element Qu1, and controls driving and pause of a pause holding switch element S3 described later according to the detected voltage. In the example of FIG. 3, the control voltage detection unit 304 includes a comparator OP1, a reference power supply REF, a resistor R1, and a wiring 303. The minus terminal (− terminal) of the comparator OP1 is connected to the output terminal of the driving switch element S1 via the resistor R1 and the wiring 303, and the plus terminal (+ terminal) is connected to the positive electrode of the reference power source REF. At the minus terminal of the comparator OP1, as described above, the change in the control terminal of the switch element Qu1 that gradually changes due to the resistance and capacitance of the switch element Qu1 and peripheral circuits and approaches the ground voltage is measured, as described above. be able to. Therefore, the comparator OP1 outputs a signal (ON control) for driving the suspension holding switch element S3 to the prevention unit via the logic circuit 302 when the voltage at the output terminal p9 becomes equal to or lower than the predetermined reference voltage of the reference power supply REF. To do.

The prevention unit includes a pause holding switch element S3 that holds the pause of the switch element Qu1, and resistors R5 and R6.
The pause holding switch element S3 is a period from when the pause switch element S2 outputs a signal to pause the switch element Qu1 until the voltage at the output terminal p9 becomes equal to or lower than a predetermined reference voltage of the reference power supply REF, a surge, etc. Therefore, the switch element Qu1 is controlled so that the switch element Qu1 is not driven. The control terminal (gate) of the suspension holding switch element S3 is connected to the output terminal of the logic circuit 302 that outputs a signal for controlling the suspension holding switch element S3 via the resistor R5 and the output terminal p13. Further, one terminal (drain) of the suspension holding switch element S3 is connected to the control terminal of the switching element Qu1, and the other terminal (source) of the suspension holding switch element S3 is connected to the ground. It is conceivable to use a MOSFET, IGBT or the like as the suspension holding switch element S3.

  In the example of FIG. 3, the control voltage detection unit 304 outputs a signal to the prevention unit via the logic circuit 302, but may output the signal without passing through the logic circuit 302. Further, the resistor R1 may not be provided, and the output terminal p9 and the negative terminal of the comparator OP1 may be directly connected. Alternatively, the resistance R1 on the wiring 303 may be smaller than the resistance R1 on the wiring 300 (broken line). This is because the resistor R2 can bear at least a part of the resistance value of the resistor R1 as a resistance value for connecting to the negative terminal of the comparator OP1.

  According to the embodiment, the input terminal of the integrated circuit 301 can be reduced by connecting the output terminal p9 connected to the other terminal of the driving switch element S1 to the negative terminal (− terminal) of the comparator OP1. . As a result, the drive unit 6a can be reduced in size. In addition, since each of the drive units 6a and 6b in FIGS. 1 and 2 can be made small, the inverter drive circuit can also be made small.

The present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.
In addition, the inverter drive circuit provided only with the drive part 6a (6b) shown in FIG. 3 without the selection parts 7a and 7b may be used. Also in that case, the integrated circuit 301 can be miniaturized, so that it can be miniaturized as an inverter drive circuit.

DESCRIPTION OF SYMBOLS 1a, 1b Low voltage circuit 2a, 2b High voltage circuit 3a, 3b Insulation part 4a, 4b Temperature detection part 5a, 5b Temperature measurement part 6a, 6b Drive part 7a, 7b Selection part 8 Control part OP1 Comparator p1 to p13 Terminals Qu1, Qd1 switch Elements R1 to R6 Resistor REF Reference power supply S1, S2, S3 Switch elements 300, 303 Wiring 301 Integrated circuit 302 Logic circuit 304 Control voltage detector

Claims (3)

A control unit provided in the inverter drive circuit for driving the inverter circuit;
A selection unit that selects predetermined temperature information from the temperature information of each of the switch elements provided in the upper arm and the lower arm of the inverter circuit, and transmits the selected predetermined temperature information to the control unit;
An inverter drive circuit comprising: The inverter drive circuit according to claim 1,
The selection unit includes:
Provided for each phase of the inverter circuit, selecting the temperature information of the switch elements of the upper arm and the lower arm for each phase;
An inverter drive circuit characterized by that. The inverter drive circuit according to claim 1,
A drive switch element for driving the switch element;
A suspending switch element for suspending the switch element;
A driving resistor connected between an output terminal of the driving switch element and a control terminal of the switch element;
A pause resistor connected between the output terminal of the pause switch element and the control terminal of the switch element;
A dormant holding switch element for holding the dormant state of the switch element;
A control voltage detector that detects a voltage of an output terminal of the driving switch element connected to the driving resistor, and controls driving and pausing of the pause holding switch element according to the detected voltage;
An inverter drive circuit comprising:

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