Control apparatus and power conversion equipment

Abstract

To suppress the main current imbalance of a semiconductor device such as IGBTs connected in parallel regardless of the circuit configuration, adjust the heat generation of the semiconductor device connected in parallel so that it is equal, and extend the service life of power conversion equipment.SOLUTION: A control apparatus for controlling a plurality of semiconductor devices connected in parallel has a difference detection section that receives outputs from a current detection section that detects the main current of each of a plurality of semiconductor devices and detects differences in the outputs of the current detection section, an analog-to-digital conversion section that adjusts the output of the difference detection section to zero, and a power supply section that outputs control voltage for the semiconductor device according to the output of the analog-to-digital conversion section.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device and a power conversion device. [Background technology]

[0002] To increase the output of a power conversion device such as an inverter, multiple semiconductor devices are usually connected in parallel. If the electrical characteristics of each semiconductor device are the same, the main current of each semiconductor device will be uniform and no imbalance in the main current will occur. However, in reality, there is variation in the characteristics of each semiconductor device. This causes an imbalance in the main current of each semiconductor device.

[0003] In order to reduce this current imbalance, technology is being developed that detects the current of each semiconductor device and adjusts the control voltage of each semiconductor device so as to make the difference between the currents zero.

[0004] Patent Document 1 discloses a current balancing circuit of parallel-connected controllable semiconductor elements, which detects the main current flowing through each main emitter of two IGBTs by the voltage of a sense resistor, uses two operational amplifiers to measure the potential difference as the voltage difference between the sense resistors, and adjusts the gate voltage of the IGBTs by turning on and off the FETs, thereby balancing the currents of the two IGBTs.

[0005] Here, IGBT is an abbreviation for Insulated Gate Bipolar Transistor, and FET is an abbreviation for Field Effect Transistor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-289442 Summary of the Invention [Problem to be solved by the invention]

[0007] The current balance circuit described in Patent Document 1 has a circuit that detects the difference in the current sense voltages of each IGBT, and adjusts the gate current so as to make the difference zero. However, the greater the variation in the characteristics of each IGBT, the greater the difference adjustment range. In order to balance the main current with high precision, the response of the operation of the circuit (operational amplifier and FET) that adjusts the gate current must be increased. When the response of the circuit operation is increased, the operation of the circuit becomes unstable due to the oscillation phenomenon of the operational amplifier, making it difficult to balance the main current with high precision. In addition, since the FET generates variations in the gate current due to temperature characteristics, it is considered that the balance operation of the main current becomes even more difficult.

[0008] An object of the present disclosure is to suppress the main current imbalance of semiconductor devices such as IGBTs connected in parallel regardless of the circuit configuration, adjust the heat generation amounts of the semiconductor devices connected in parallel to be equal, and extend the service life of the power conversion device.

Means for Solving the Problems

[0009] The control device of the present disclosure controls a plurality of semiconductor devices connected in parallel, and includes a difference detection unit that receives the output of a current detection unit that detects the main current of each of the plurality of semiconductor devices and detects the difference in the output of the current detection unit, an analog-digital conversion unit that adjusts the output of the difference detection unit to zero, and a power supply unit that outputs a control voltage of the semiconductor device according to the output of the analog-digital conversion unit.

Effects of the Invention

[0010] According to the present disclosure, it is possible to suppress the main current imbalance of semiconductor devices such as IGBTs connected in parallel regardless of the circuit configuration, adjust the heat generation amounts of the parallel-connected semiconductor devices to be equal, and extend the life of the power conversion device. Furthermore, according to the present disclosure, it is possible to provide a low-cost power conversion device by eliminating the need for pairing selection work at the time of shipment to determine the characteristic variations (on-state voltage, threshold value, etc.) of the parallel-connected semiconductor devices. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating a current balance control device according to an embodiment of the present invention; [Figure 2] 3A and 3B are diagrams for explaining the operation of the current balance control device of the embodiment; [Figure 3] 1 is a circuit configuration diagram showing an inverter device to which a current balance control device according to an embodiment of the present invention is applied; DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure relates to a control device for a semiconductor device and a power conversion device using the same.

[0013] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0014] The configuration described below can also be applied to power conversion devices for in-vehicle, industrial, and home use. [Example]

[0015] FIG. 1 is a schematic diagram showing the configuration of a current balance control device according to an embodiment of the present invention.

[0016] The current balance control device 1 (hereinafter also simply referred to as "control device") shown in this figure has the function of balancing the main currents of two semiconductor devices 100, 101 (IGBTs) connected in parallel with high precision.

[0017] The current balance control device 1 is connected to a semiconductor device 100, which is a reference element, and a semiconductor device 101, which is a parallel element. A diode 110 is electrically connected in parallel to the semiconductor device 100. A diode 111 is electrically connected in parallel to the semiconductor device 101. The semiconductor device 100 is connected in parallel to the semiconductor device 101.

[0018] The semiconductor device 100, which is an IGBT, has a collector electrode and an emitter electrode, and a diode 110 is electrically connected between them. The IGBT is provided with a gate electrode in addition to the collector electrode and the emitter electrode. The semiconductor device 101 has a similar configuration.

[0019] Current sensors 120 and 121 (current detection units) are also connected to the current balance control device 1. The current sensor 120 is connected to the semiconductor device 100. The current sensor 121 is connected to the semiconductor device 101.

[0020] The current balance control device 1 includes a current detection unit 13, a difference detection unit 14 that detects a difference from the output of the current detection unit 13, a PWM control unit 15 (pulse width conversion unit) that PWM converts the output voltage of the difference detection unit 14, a power supply unit 16 that outputs a control voltage VGE for the semiconductor device 101 from the pulse output of the PWM control unit 15, a drive unit 17 that drives the semiconductor device 101, and a drive unit 18 that drives the semiconductor device 100. Here, PWM is an abbreviation for pulse width modulation, and VGE is an abbreviation for the gate-emitter voltage of the IGBT.

[0021] The PWM control unit 15 is a type of analog-to-digital conversion circuit. The analog-to-digital conversion circuit applicable to the current balance control device according to the present disclosure is not limited to a PWM control unit, but may be any type of conversion circuit that converts an analog signal to a digital signal, such as a PAM control unit. Here, PAM is an abbreviation for pulse amplitude modulation.

[0022] The current sensor 120 is connected to the emitter side of the semiconductor device 100 and detects the main current. In this figure, the current sensor 120 is represented by a resistance and an inductance, but it also includes parasitic resistance and parasitic inductance of the main terminals and internal wiring within the IGBT module.

[0023] The driving unit 18 sends a driving pulse voltage VGE0 to the semiconductor device 100, causing the semiconductor device 100 to perform a switching operation. As a result, when a main current I0 flows, a voltage V0 is generated in the current sensor 120, which is input to the current detection unit 13. In addition, the semiconductor device 101 connected in parallel to the semiconductor device 100 also performs a switching operation in response to the driving pulse output from the driving unit 17. As a result, when a main current I1 flows, a voltage V1 is generated in the current sensor 121, which is input to the current detection unit 13.

[0024] The current detection unit 13 has a function of amplifying the voltage values V0 and V1 received from the current sensors 120 and 121 to predetermined voltage values V0' and V1', respectively. These output voltages V0' and V1' are input to the difference detection unit 14. The difference detection unit 14 outputs a differential voltage (V1'-V0'). The differential voltage is input to the PWM control unit 15. The PWM control unit 15 has a function of converting the differential voltage (V1'-V0') into a pulse width corresponding to the magnitude of the differential voltage. In accordance with this pulse width, the power supply unit 16 outputs a control voltage VGE1 for the semiconductor device 101. When the control voltage VGE1 changes, the drive pulse voltage (VGE1) for the semiconductor device 101 output from the drive unit 17 also changes.

[0025] Figure 2 is a diagram for explaining the operation of the current balance control device of the present embodiment. In the following description, the reference numerals of the respective components are those in FIG. 1.

[0026] In FIG. 2, three types of waveforms are shown according to the magnitude relationship between the main current I0 of the semiconductor device 100 which is a reference element and the main current I1 of the semiconductor device 101 which is a parallel element. In this figure, the upper row is the case where (1) I1 > I0, the middle row is the case where (2) I1 = I0, and the lower row is the case where (3) I1 < I0.

[0027] First, the PWM operation in the case of (1) I1 > I0 will be described.

[0028] The main currents I1 and I0 of the semiconductor devices 101 and 100 are input to the current detection unit 13 as voltages V1 and V0, level-converted to V1' and V0', detected as a differential voltage (V1' - V0') by the differential detection unit 14, and input to the PWM control unit 15.

[0029] In the PWM control unit 15, it is converted into a pulse width according to the magnitude relationship between a predetermined triangular wave and the differential voltage (V1' - V0'). That is, when the differential voltage (V1' - V0') is positive, the pulse width is narrowed; when the differential voltage (V1' - V0') is zero, the pulse width is maintained at a predetermined pulse width; and when the differential voltage (V1' - V0') is negative, the pulse width is widened. As a result, the drive pulse voltage VGE1 of the semiconductor device 101 becomes lower than the drive pulse voltage VGE0 of the semiconductor device 100.

[0030] Similarly, in the cases of (2) I1 = I0 and (3) I1 < I0, the pulse width is also changed according to the differential voltage (V1' - V0'). As a result, in the case of (2), the drive pulse voltage VGE1 of the semiconductor device 101 becomes the same value as the drive pulse voltage VGE0 of the semiconductor device 100. Also, in the case of (3), the drive pulse voltage VGE1 of the semiconductor device 101 becomes higher than the drive pulse voltage VGE0 of the semiconductor device 100.

[0031] In summary, when the output of the differential detection unit 14 is positive, the PWM control unit 15 narrows the pulse width; when the output of the differential detection unit 14 is zero, the PWM control unit 15 maintains the pulse width at a predetermined value; and when the output of the differential detection unit 14 is negative, the PWM control unit 15 widens the pulse width.

[0032] As described above, according to this embodiment, it is possible to suppress the imbalance of the main current of the parallel-connected semiconductor devices, make the heat generation amounts of the parallel-connected semiconductor devices substantially equal, and realize the long life of the power conversion device including the semiconductor devices. In addition, since it is not necessary to perform the pairing and sorting operation of the characteristic variations (such as on-voltage and threshold value) of each semiconductor device at the time of shipment, the cost can be reduced, and a low-cost power conversion device can be provided.

[0033] FIG. 3 is a circuit configuration diagram showing an inverter device (power conversion device) to which the current balance control device of this embodiment is applied.

[0034] As shown in this figure, the inverter device 300 includes a power module 301, a drive circuit unit 302, and an electrolytic capacitor 306 (SEC). An electric motor control device 310, a motor 320, and a high-voltage battery 330 (BAT) are connected to the inverter device 300. The drive circuit unit 302 is the current balance control device of FIG. 1.

[0035] The power module 301 includes a U-phase arm 303 (Au), a V-phase arm 304 (Av), and a W-phase arm 305 (Aw), and constitutes a main circuit for power conversion. The power module 301 operates in response to a drive signal output from the drive circuit unit 302, converts the DC power supplied from the high-voltage battery 330 into three-phase AC power, and supplies it to the stator windings of the motor 320. The main circuit of the power module 301 is a three-phase bridge circuit, and three series circuits are electrically connected in parallel between the positive electrode side and the negative electrode side of the high-voltage battery 330. The series circuit is also called an arm and is composed of two power semiconductor modules.

[0036] The arm is configured such that the upper arm side (positive electrode side) power semiconductor module and the lower arm side (negative electrode side) power semiconductor module are electrically connected in series. Each power semiconductor module has a semiconductor device 100 which is a reference element shown in FIG. 1 and a semiconductor device 101 which is a parallel element. Therefore, one arm includes four semiconductor devices. Since the power module 301 is composed of a U-phase arm 303 (Au), a V-phase arm 304 (Av) and a W-phase arm 305 (Aw), it includes a total of 12 semiconductor devices in total.

[0037] Note that an n-channel MOSFET (metal oxide semiconductor field effect transistor) may be used as the semiconductor device. The MOSFET has three electrodes: a drain electrode, a source electrode and a gate electrode. Also, a parasitic diode whose forward direction is from the source electrode to the drain electrode is electrically connected between the drain electrode and the source electrode.

[0038] The midpoint of the U-phase arm 303 (Au) (the connection part between the emitter electrode of the upper arm side power semiconductor module and the collector electrode of the lower arm side (negative electrode side) power semiconductor module) is electrically connected to the U-phase stator winding of the motor 320. Similarly, the midpoint of the V-phase arm 304 (Av) is electrically connected to the V-phase stator winding of the motor 320, and the midpoint of the W-phase arm 305 (Aw) is electrically connected to the W-phase stator winding of the motor 320.

[0039] An electrolytic capacitor 306 for smoothing is electrically connected between the positive electrode side and the negative electrode side of the high-voltage battery 330 in order to suppress fluctuations in the DC voltage generated by the operation of the power semiconductor module.

[0040] In the power module 301, semiconductor devices are mounted on an insulating substrate on a base enclosed by a case. In the power module 301, the semiconductor devices, the semiconductor devices and input terminals, and the semiconductor devices and output terminals are electrically connected by connecting conductors such as aluminum wires or plate-shaped conductors to form a three-phase bridge circuit. The base is made of a thermally conductive material such as copper or aluminum. The underside of the base is cooled by a coolant such as air or cooling water. Fins or the like are provided on the underside of the base to improve the cooling efficiency of the coolant. The insulating substrate is made of an insulating material such as aluminum nitride, and wiring patterns are metallized on both sides. The semiconductor devices have electrodes on both sides. The base and the insulating substrate, and the insulating substrate and the semiconductor devices are joined by a joining material such as solder.

[0041] The driving circuit section 302 is electrically connected to the gate electrode of the semiconductor device.

[0042] The motor control device 310 has a microcomputer that calculates control values. The motor control device 310 calculates control values for operating the power semiconductor elements (semiconductor devices) of the power module 301 based on a plurality of input signals, and outputs the control values obtained as a result of the calculation to the drive circuit unit 302 as control signals Vpu*, Vpv*, Vpw*, Vnu*, Vnv*, and Vnw*. In response to these control signals, the drive circuit unit 302 outputs drive signals Vpu and Vnu to the U-phase arm 303 (Au), drive signals Vpv and Vnv to the V-phase arm 304 (Av), and drive signals Vpw and Vnw to the W-phase arm 305 (Aw).

[0043] The microcomputer of the motor control device 310 receives as input signals a torque command signal (torque command value) τ, a rotation speed command signal (rotation speed command value) n*, detection signals (current values of u-phase, v-phase, w-phase) iu, iv, iw, and a detection signal (magnetic pole position of the rotor) θ.

[0044] The detection signals iu, iv, and iw are respectively output from current sensors Cu, Cv, and Cw. The detection signal θ is output from a magnetic pole position sensor.

[0045] The current sensors Cu, Cv, and Cw are for detecting the u-phase, v-phase, and w-phase currents iu, iv, and iw supplied from the power module 301 to the stator windings of the stator of the motor 320, and are composed of a shunt resistor, a current transformer, and the like.

[0046] The magnetic pole position sensor is for detecting the magnetic pole position θ of the rotor of the motor 320, and is composed of a resolver, an encoder, a Hall element, a Hall IC, and the like.

[0047] As described above, according to this embodiment, it is possible to suppress the main current imbalance of the semiconductor devices connected in parallel, and to realize uniform heat generation and long life of each semiconductor device. In addition, the pairing selection operation at the time of shipment for the characteristic variations (such as on-voltage and threshold value) of each semiconductor device becomes unnecessary, and a low-cost power conversion device can be provided. Furthermore, by using an analog-digital conversion unit such as a PWM control unit, the response of the gate current for adjusting the current difference becomes faster, and the stability of the control circuit against oscillation also increases. Therefore, it is possible to balance the main current with higher accuracy compared to the prior art.

[0048] Note that the semiconductor device shown in the above embodiment can be used as a control target as long as it is a semiconductor element, an electronic circuit, or the like having the same function as an IGBT.

Explanation of Reference Numerals

[0049] 1: Current balance control device, 13: Current detection unit, 14: Difference detection unit, 15: PWM control unit, 16: Power supply unit, 17, 18: Drive unit, 100, 101: Semiconductor device, 110, 111: Diode, 120, 121: Current sensor, 300: Inverter device, 301: Power module, 302: Drive circuit unit, 303: U-phase arm, 304: V-phase arm, 305: W-phase arm, 306: Electrolytic capacitor, 310: Motor control device, 320: Motor, 330: High-voltage battery.

Claims

1. A control device for controlling a plurality of semiconductor devices connected in parallel, comprising: a difference detection unit that receives the output of a current detection unit that detects the main current of each of the plurality of semiconductor devices and detects the difference in the output of the current detection unit; an analog-to-digital conversion unit that adjusts the output of the difference detection unit to zero; a power supply unit that outputs a control voltage for the semiconductor device according to the output of the analog-to-digital conversion unit.

2. The control device according to claim 1, wherein the analog-to-digital conversion unit is a PWM control unit that converts the output of the difference detection unit into a pulse width.

3. The PWM control unit: narrows the pulse width when the output of the difference detection unit is positive; maintains a predetermined pulse width when the output of the difference detection unit is zero; widens the pulse width when the output of the difference detection unit is negative.

4. The semiconductor device is an insulated gate bipolar transistor or a metal oxide semiconductor field effect transistor.

5. A power conversion device comprising: the control device according to any one of claims 1 to 4; the semiconductor device; and the current detection unit.

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