Communication circuits, semiconductor modules

Abstract

This invention provides a communication circuit that enables information to be transmitted between circuits with different reference voltages. [Solution] The communication circuit comprises a first switching element on the power supply side, a first capacitor having a first electrode and a second electrode connected in series with the first switching element and connected to the connection point with the second switching element on the ground side, a second capacitor having a third electrode to which a ground voltage is applied and a fourth electrode, a diode having an anode connected to the fourth electrode and a cathode, a first switch located between the cathode and the second electrode, and a charging circuit that charges the second capacitor when the first switching element is on and the second switching element is off, wherein the first switch is turned on when the first switching element is off and the second switching element is on during a communication period in which an abnormal signal indicating an abnormality of the first switching element is output.

Description

Technical Field

[0001] The present invention relates to a communication circuit and a semiconductor module.

Background Art

[0002] There is a module including a semiconductor chip on which a switching element such as an IGBT (Insulated Gate Bipolar Transistor) and a diode for temperature detection are formed, and a drive circuit (see, for example, Patent Documents 1 and 2). Such a module is generally called an IPM (Intelligent Power Module) for a power conversion device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a bridge circuit in which high-side and low-side switching elements are provided in series, when current flows through the switching element, the temperature of the switching element rises and it enters an overheated state, the switching element may be destroyed. In addition, the rise or fall of the temperature of the switching element affects the life of the switching element. Therefore, for example, it is preferable that information such as the temperature of the switching element and whether an overcurrent has occurred in the switching element can be communicated to the outside.

[0005] However, for example, communicating information between an integrated circuit that drives high-side switching elements and an integrated circuit that drives low-side switching elements was difficult because the reference voltages in each integrated circuit were different.

[0006] The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a communication circuit that communicates information between circuits with different reference voltages. [Means for solving the problem]

[0007] The first aspect of the communication circuit of the present invention, which solves the aforementioned problems, comprises a first switching element on the power supply side, a first capacitor having a first electrode and a second electrode connected in series with the first switching element and connected to the connection point with a second switching element on the ground side, a second capacitor having a third electrode to which a ground voltage is applied and a fourth electrode, a diode having an anode connected to the fourth electrode and a cathode, a first switch located between the cathode and the second electrode, and a charging circuit that charges the second capacitor when the first switching element is on and the second switching element is off, wherein the first switch is turned on when the first switching element is off and the second switching element is on during a communication period in which an abnormal signal indicating an abnormality of the first switching element is output.

[0008] A second aspect of the main communication circuit of the present invention that solves the aforementioned problems is a communication circuit comprising: a first switching element on the power supply side; a first capacitor having a first electrode and a second electrode connected in series with the first switching element and connected to the connection point with a second switching element on the ground side; a second capacitor having a third electrode to which a ground voltage is applied and a fourth electrode; a diode having an anode connected to the fourth electrode and a cathode connected to the second electrode; and a charging circuit that charges the second capacitor when the first switching element is on and the second switching element is off during a communication period in which an abnormal signal indicating an abnormality of the first switching element is output.

[0009] The main semiconductor module of the present invention that solves the aforementioned problems comprises a first switching element on the power supply side, a second switching element connected in series with the first switching element and on the ground side, a first drive circuit for driving the first switching element, a second drive circuit for driving the second switching element, a first capacitor having a first electrode and a second electrode connected to the connection point of the first and second switching elements, a second capacitor having a third electrode to which a ground voltage is applied and a fourth electrode, a diode having an anode and a cathode connected to the fourth electrode, a first switch located between the cathode and the second electrode, and a charging circuit for charging the second capacitor when the first switching element is on and the second switching element is off, wherein the first switch is turned on when the first switching element is off and the second switching element is on during a communication period in which an abnormal signal indicating an abnormality of the first switching element is output. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a communication circuit that communicates information between circuits with different reference voltages. [Brief explanation of the drawing]

[0011] [Figure 1]It is a diagram showing an example of the overall configuration of the motor drive device 1. [Figure 2] It is a diagram showing an example of the configuration of the semiconductor module 10. [Figure 3] It is a diagram showing an example of the configuration of the HVIC 20a. [Figure 4] It is a diagram showing an example of the configuration of the LVIC 23a. [Figure 5] It is a diagram showing an example of the configuration of the upper arm transmission unit 102 and the lower arm reception unit 220. [Figure 6] It is a diagram showing an example of the operation of the upper arm transmission unit 102 and the lower arm reception unit 220. [Figure 7] It is a diagram showing an example of the configuration of the HVIC 20b. [Figure 8] It is a diagram showing an example of the configuration of the LVIC 23b. [Figure 9] It is a diagram showing an example of the configuration of the upper arm transmission unit 104 and the lower arm reception unit 230. [Figure 10] It is a diagram showing an example of a pattern. [Figure 11] It is a diagram showing an example of the configuration of the HVIC 20c. [Figure 12] It is a diagram showing an example of the configuration of the LVIC 23c. [Figure 13] It is a diagram showing an example of the configuration of the upper arm reception unit 105 and the lower arm transmission unit 240.

Embodiments for Carrying Out the Invention

[0012] From the description in this specification and the accompanying drawings, at least the following matters become clear. Hereinafter, preferred embodiments of the present invention will be described while referring to the drawings. The same or equivalent components, members, etc. shown in each drawing are denoted by the same reference numerals, and repeated explanations are omitted as appropriate. =====This Embodiment===== <<<Regarding the Overall Configuration of the Motor Drive Device 1>>> FIG. 1 is a block diagram showing the overall configuration of the motor drive device 1 in this embodiment.

[0013] The motor drive device 1 of this embodiment controls the semiconductor module 10 based on instructions from the microcomputer 11 and drives a three-phase motor 12 as a load.

[0014] The motor drive device 1 includes a semiconductor module 10 and a microcomputer 11.

[0015] ==Semiconductor Module 10== The semiconductor module 10 in FIG. 2 is an inverter circuit that drives the three-phase motor 12 based on drive signals SinU, SinV, SinW, SinX, SinY, SinZ from the microcomputer 11. The semiconductor module 10 is an IPM including HVICs 20 - 22, LVIC 23, IGBTs 30, 33, 36, 40, 43, 46, freewheeling diodes 31, 34, 37, 41, 44, 47, temperature detection diodes 32, 35, 38, 42, 45, 48, and diodes D1 - D3. Further, the semiconductor module 10 is provided with terminals VinU, VinV, VinW, VinX, VinY, VinZ, and terminals P, U, V, W, N. Although other terminals are provided, the description is omitted.

[0016] Each of HVICs 20 - 22 is an integrated circuit that drives each of IGBTs 30, 33, 36 based on each of the drive signals SinU, SinV, SinW from the microcomputer 11. IGBT 30 is a switching element of the U phase that is an element on the power supply voltage Vcc side (i.e., the power supply side) of the DC power supply 13, and applies the power supply voltage Vcc applied to the terminal P to the three-phase motor 12 via the terminal U. Also, IGBT 33 is a switching element of the V phase that is an element on the power supply side, and applies the power supply voltage Vcc applied to the terminal P to the three-phase motor 12 via the terminal V. Also, IGBT 36 is a switching element of the W phase that is an element on the power supply side, and applies the power supply voltage Vcc applied to the terminal P to the three-phase motor 12 via the terminal W. Note that IGBTs 30, 33, 36 correspond to the "first switching elements".

[0017] Furthermore, LVIC23 is an integrated circuit that drives IGBTs 40, 43, and 46 respectively based on the drive signals SinX, SinY, and SinZ from the microcontroller 11. IGBT 40 is an X-phase switching element, which is the grounded element, and applies the ground voltage to the 3-phase motor 12 via terminal U. IGBT 43 is a Y-phase switching element, which is the grounded element, and applies the ground voltage to the 3-phase motor 12 via terminal V. IGBT 46 is a Z-phase switching element, which is the grounded element, and applies the ground voltage to the 3-phase motor 12 via terminal W. Note that IGBTs 40, 43, and 46 correspond to the "second switching elements".

[0018] Furthermore, each of the freewheeling diodes 31, 34, 37, 41, 44, and 47 is a component that allows current to flow back when each of the IGBTs 30, 33, 36, 40, 43, and 46 is turned off.

[0019] Diodes 32, 35, 38, 42, 45, and 48 are detection elements that detect the temperature of IGBTs 30, 33, 36, 40, 43, and 46, respectively, and are positioned in the vicinity of IGBTs 30, 33, 36, 40, 43, and 46.

[0020] In this embodiment, IGBTs 30, 33, 36, 40, 43, and 46 are used as switching elements. However, the system is not limited to IGBTs; for example, bipolar transistors or MOS transistors may also be used.

[0021] Diode D1 has its anode connected to LVIC23 and its cathode connected to HVIC20. Diode D2 has its anode connected to LVIC23 and its cathode connected to HVIC21. Diode D3 has its anode connected to LVIC23 and its cathode connected to HVIC22. The functions of diodes D1 to D3 will be described later. Note that diodes D1 to D3 have a higher withstand voltage than the power supply voltage Vcc because they connect HVIC20, 21, and 22, whose reference voltage changes to a voltage level of voltage Vcc (for example, up to 400V) or the ground voltage, to LVIC23, whose reference voltage is the ground voltage.

[0022] <<<First Embodiment>>> ==HVIC20a== Figure 3 shows an example of the configuration of HVIC20a, which is one embodiment of HVIC20. HVIC20a drives the IGBT30 based on the drive signal SinU from the microcontroller 11. Furthermore, HVIC20a detects an abnormality in the IGBT30 (e.g., overheating) based on the forward voltage VF of the diode 32 between terminals tmp_A and tmp_C, and communicates this information to LVIC23a via diode D1 in Figure 2.

[0023] The HVIC20a consists of a drive circuit 100, a detection circuit 101, an upper arm transmitter 102, and terminals IN, OUT, DI_IN, tmp_A, tmp_C, and GND. The drive circuit 100 drives the IGBT 30 by outputting a drive voltage from terminal OUT based on a drive signal SinU from terminal IN. The detection circuit 101 flows a predetermined current from terminal tmp_A to diode 32 and detects the forward voltage VF of diode 32 generated between terminals tmp_A and tmp_C. When the forward voltage VF falls below a predetermined level (i.e., the detected temperature rises above the predetermined temperature), the detection circuit 101 outputs a signal DET indicating overheating of the IGBT 30. The drive circuit 100 corresponds to the "first drive circuit".

[0024] In this embodiment, the detection circuit 101 detects overheating. However, if the IGBT 30 is accompanied by a sense IGBT, the detection circuit 101 may detect overcurrent in the IGBT 30 and output a signal DET indicating overcurrent in the IGBT 30 when an abnormality (e.g., overcurrent) occurs. Alternatively, the detection circuit 101 may detect both overheating and overcurrent and output a signal DET indicating an abnormality in the IGBT 30 (e.g., at least one of overheating and overcurrent). Furthermore, diodes 32, 35, 38, 42, 45, and 48 correspond to "detection elements".

[0025] The upper arm transmitter 102, as will be described in detail later, communicates information to the LVIC 23a indicating an abnormality in the IGBT 30 (e.g., overheating) based on the signal DET. The cathode of diode D1 (see Figure 2) is connected to terminal DI_IN, and the voltage Vu of terminal U in Figure 2, which fluctuates depending on whether IGBTs 30 and 40 are on or off, is applied to terminal GND.

[0026] ==LVIC23a== Figure 4 shows an example of the configuration of LVIC23a, which is one embodiment of LVIC23. LVIC23a drives IGBTs 40, 43, and 46 based on drive signals SinX, SinY, and SinZ from the microcontroller 11. Furthermore, LVIC23a detects information communicated by the upper arm transmitter 102 based on the voltages of terminals DI_X, DI_Y, and DI_Z to which the anodes of diodes D1 to D3 are connected, and communicates the detection results to the microcontroller 11 via terminals Sout_X, Sout_Y, and Sout_Z, respectively.

[0027] The LVIC23a consists of drive circuits 200-202, lower arm receiving sections 220-222, and terminals IN_X, IN_Y, IN_Z, OUT_X, OUT_Y, OUT_Z, DI_X, DI_Y, DI_Z, Sout_X, Sout_Y, Sout_Z, and GND.

[0028] The drive circuits 200-202 drive IGBT40, IGBT43, and IGBT46 respectively based on the drive signals SinX, SinY, and SinZ from terminals IN_X, IN_Y, and IN_Z. Note that drive circuits 200-202 correspond to the "second drive circuit".

[0029] The lower arm receiving units 220-222 receive information indicating anomalies communicated from the upper arm transmitting unit 102 of the HVIC20a, 21a, and 22a, as will be described in detail later. A ground voltage is applied to the GND terminal.

[0030] ==Configuration of Upper Arm Transmitter 102== Figure 5 shows an example of the configuration of the upper arm transmitter 102 included in HVIC20a and the lower arm receiver 220 included in LVIC23a. The upper arm transmitter 102, the lower arm receiver 220, and diode D1 constitute the communication circuit 15.

[0031] The upper arm transmitter 102 transmits information indicating an abnormality (e.g., overheating) of the IGBT 30 to the lower arm receiver 220 based on the signal DET from the detection circuit 101. The upper arm transmitter 102 is composed of a capacitor C1, switches SW1 and SW2, and a control circuit U1a.

[0032] ===Capacitor C1 and Switch SW1=== Capacitor C1 has one electrode connected to the connection point Nu between IGBT30 and IGBT40, which is connected in series with IGBT30, and the cathode of diode D1 is connected to the other electrode via switch SW1. In other words, the reference voltage of capacitor C1 is voltage Vu. Capacitor C1 corresponds to the "first capacitor," one electrode of capacitor C1 corresponds to the "first electrode," the other electrode of capacitor C1 corresponds to the "second electrode," and switch SW1 corresponds to the "first switch."

[0033] Switch SW2 is connected in parallel with capacitor C1 to discharge the capacitor C1; that is, switch SW2 is located between the other electrode of capacitor C1 and the connection point Nu. Switch SW2 corresponds to the "second switch".

[0034] Control circuit U1a turns on switch SW1 when IGBT30 is off and IGBT40 is on during the communication period in which the abnormal signal DET indicating an abnormality of IGBT30 is output. Specifically, when the detection circuit 101 outputs signal DET and it is time to start communication with the lower arm receiver 220 (i.e., the start of communication), control circuit U1a turns on switch SW1 when IGBT30 is off and IGBT40 is on during the communication period. In other words, as will be described in detail later, control circuit U1a turns on switch SW1 when it is time to start communication and the voltage Vu becomes the ground voltage. Details of the timing for starting communication will be described later.

[0035] Then, when IGBT30 is turned on and IGBT40 is turned off, control circuit U1a turns on switch SW2 and discharges the charge stored in capacitor C1. In other words, as will be explained in detail later, control circuit U1a turns on switch SW2 when voltage Vu becomes equal to the power supply voltage Vcc. Note that the voltage Vu at the connection point Nu of IGBT30 and IGBT40 is applied to terminal gnd of control circuit U1a, and the voltage of the power supply V2, which is referenced to the voltage Vu at connection point Nu, is applied to terminal vdd. Control circuit U1a corresponds to a "switch control circuit".

[0036] ==Configuration of the lower arm receiving unit 220== The lower arm receiving unit 220 receives information from the upper arm transmitting unit 102. The lower arm receiving unit 220 is composed of a capacitor C2, a charging circuit 300, and a signal output circuit 301.

[0037] ===Capacitor C2=== Capacitor C2 has a ground voltage applied to one electrode, and the anode of diode D1 is connected to the other electrode. Capacitor C2 corresponds to the "second capacitor," one electrode of capacitor C2 corresponds to the "third electrode," and the other electrode of capacitor C2 corresponds to the "fourth electrode."

[0038] ===Charging circuit 300=== The charging circuit 300 is a circuit that charges capacitor C2, and charges capacitor C2 when IGBT 30 is ON and IGBT 40 is OFF during the communication period. The charging circuit 300 consists of a power supply V1 and a switch SW3. Switch SW3 is turned ON when IGBT 30 is ON and IGBT 40 is OFF. Then, capacitor C2 is charged by the voltage V1 of power supply V1. On the other hand, switch SW3 is turned OFF when IGBT 30 is OFF and IGBT 40 is ON so that capacitor C1 is not charged by voltage V1.

[0039] The signal output circuit 301 causes the charging circuit 300 to charge capacitor C2 and outputs a signal Sout_X corresponding to the charging voltage of capacitor C2. Specifically, the signal output circuit 301 causes the charging circuit 300 to charge capacitor C2 when IGBT 30 is ON and IGBT 40 is OFF. Also, when IGBT 30 is OFF and IGBT 40 is ON, the signal output circuit 301 outputs a signal Sout_X corresponding to the charging voltage of capacitor C2, which changes depending on whether or not charge has moved from capacitor C2 to capacitor C1 via diode D1. The signal output circuit 301 is composed of a control circuit U2a and a comparator U3. The signal output circuit 301 corresponds to the "first signal output circuit".

[0040] When IGBT30 is ON and IGBT40 is OFF, control circuit U2a turns on switch SW3 to charge capacitor C2 in the charging circuit 300. Control circuit U2a also outputs a signal Sout_X corresponding to the logic level of the signal comp_o from comparator U3.

[0041] Comparator U3 compares the charging voltage of capacitor C2 with a reference voltage Vref. Specifically, if the charging voltage V_C2 of capacitor C2 is equal to voltage V1 and higher than the reference voltage VREF, comparator U3 outputs a high-level signal comp_o (hereinafter referred to as "H" level).

[0042] On the other hand, comparator U3 outputs a low-level signal comp_o (hereinafter referred to as "L" level) when the charge stored in capacitor C2 moves to capacitor C1 via diode D1, causing the charging voltage of capacitor C2 to be lower than the reference voltage Vref.

[0043] As a result, information indicating the abnormality of IGBT30 detected by HVIC20a is communicated from HVIC20a to LVIC23a.

[0044] Figure 6 shows an example of the operation of the upper arm transmitter 102 and the lower arm receiver 220. When the drive signal SinU is at a "H" level, IGBT30 is turned on, and when the drive signal SinU is at a "L" level, IGBT30 is turned off. Also, when the drive signal SinX is at a "H" level, IGBT40 is turned on, and when the drive signal SinX is at a "L" level, IGBT40 is turned off.

[0045] In other words, IGBT30 and IGBT40 are switched on and off complementaryly. When IGBT30 is on, the voltage Vu is the power supply voltage Vcc, and when IGBT40 is on, the voltage Vu is the ground voltage. SW1 to SW3 are indicated as "short" when each switch is on and "open" when each switch is off. The detection circuit 101 outputs a signal DET indicating an abnormality in IGBT30 between times t4 and t5, and the abnormality in IGBT30 is resolved after time t6.

[0046] At time t0, the drive signal SinU becomes "H" level, turning IGBT30 on, and the drive signal SinX becomes "L" level, turning IGBT40 off. At this time, the control circuit U1a turns off switch SW1 and turns on switch SW2, discharging the charge stored in capacitor C1. Meanwhile, switch SW3 is turned on, and capacitor C2 is charged by the charging circuit 300 based on voltage V1, and the charging voltage of capacitor C2 becomes voltage V1.

[0047] At time t1, the drive signal SinU becomes "L" level, turning IGBT30 off, and the drive signal SinX becomes "H" level, turning IGBT40 on. At this time, the control circuit U1a turns off switch SW1 because the detection circuit 101 has not output the signal DET indicating an abnormality in IGBT30, and turns off SW2 because capacitor C1 has already discharged. Also, SW3 is turned off to prevent capacitor C1 from being charged by voltage V1. Furthermore, the comparator U3 outputs a signal comp_o at "H" level because the voltage across capacitor C2 is equal to voltage V1.

[0048] At time t2, the upper arm transmitting unit 102 and the lower arm receiving unit 220 perform the same operations as at time t0, capacitor C1 is discharged, and capacitor C2 is charged based on voltage V1.

[0049] At time t3, the upper arm transmitting unit 102 and the lower arm receiving unit 220 perform the same operations as at time t1.

[0050] At time t4, the upper arm transmitting unit 102 and the lower arm receiving unit 220 perform the same operations as at time t0.

[0051] At time t5, the drive signal SinU becomes "L" level, turning IGBT30 off, and the drive signal SinX becomes "H" level, turning IGBT40 on. At this time, between times t4 and t5, the detection circuit 101 raises the signal DET indicating an abnormality in IGBT30, creating a timing for communicating information to the lower arm receiver 220 (i.e., the timing to start communication). Therefore, the control circuit U1a turns on switch SW1 during the communication period when the abnormality signal DET indicating an abnormality in IGBT30 is output, and turns off SW2 because capacitor C1 has already discharged. Also, SW3 is turned off to prevent capacitor C1 from being charged by voltage V1. Then, the charge stored in capacitor C2 moves to capacitor C1 via diode D1. Therefore, the charging voltage of capacitor C2 becomes lower than the reference voltage Vref. Consequently, the comparator U3 outputs a "L" level signal comp_o because the charging voltage of capacitor C2 is lower than the reference voltage Vref. Furthermore, the same operation will be repeated from time t6 onwards.

[0052] Thus, by combining at least capacitors C1 and C2, diode D1, and switch SW1, a communication circuit can be provided that communicates information between circuits with different reference voltages.

[0053] <<<Second Embodiment>>> Figure 7 shows an example configuration of HVIC20b, which is one embodiment of HVIC20. Similar to HVIC20a, HVIC20b drives the IGBT30 based on the drive signal SinU from the microcontroller 11. Furthermore, HVIC20b detects the temperature of the IGBT30 based on the forward voltage VF of the diode 32 between terminals tmp_A and tmp_C, and communicates this information to LVIC23b.

[0054] The HVIC20b consists of a drive circuit 100, a conversion circuit 103, an upper arm transmitter 104, and terminals IN, OUT, DI_IN, tmp_A, tmp_C, and GND. The conversion circuit 103 flows a predetermined current from terminal tmp_A to diode 32, detects the forward voltage VF of diode 32 generated between terminals tmp_A and tmp_C, converts the forward voltage VF into temperature, and outputs a signal DATA indicating the temperature of IGBT 30.

[0055] The upper arm transmitter 104, as will be described in detail later, communicates information indicating the temperature of the IGBT 30 to the LVIC 23b based on the signal DATA. The cathode of diode D1 (see Figure 2) is connected to terminal DI_IN, and the voltage Vu of the connection point Nu, which varies depending on whether IGBTs 30 and 40 are on or off, is applied to terminal GND.

[0056] Figure 8 shows an example of the configuration of LVIC23b, which is one embodiment of LVIC23. LVIC23b drives IGBTs 40, 43, and 46 based on drive signals SinX, SinY, and SinZ from the microcontroller 11. Furthermore, LVIC23b detects information communicated by the upper arm transmitter 104 based on the voltages of terminals DI_X, DI_Y, and DI_Z to which the anodes of diodes D1 to D3 are connected, and communicates the detection results to the microcontroller 11 via terminals Sout_X0, Sout_X1, Sout_Y0, Sout_Y1, Sout_Z0, and Sout_Z1, respectively.

[0057] The LVIC23b consists of drive circuits 200-202, lower arm receiving sections 230-232, and terminals IN_X, IN_Y, IN_Z, OUT_X, OUT_Y, OUT_Z, DI_X, DI_Y, DI_Z, Sout_X1, Sout_X2, Sout_Y1, Sout_Y2, Sout_Z1, Sout_Z2, and GND.

[0058] The lower arm receiving units 230-232 receive information communicated from the upper arm transmitting unit 104 of the HVIC20b, 21b, and 22b, as will be described in detail later. A ground voltage is applied to the GND terminal.

[0059] ==Configuration of Upper Arm Transmitter 104== Figure 9 shows an example of the configuration of the upper arm transmitter 104 included in HVIC20b and the lower arm receiver 230 included in LVIC23b. The upper arm transmitter 104, the lower arm receiver 230, and diode D1 constitute the communication circuit 16.

[0060] The upper arm transmitter 104 transmits information indicating the temperature of the IGBT 30 to the lower arm receiver 230 based on the signal DATA from the conversion circuit 103. The upper arm transmitter 104 is composed of capacitors C1-1 and C1-2, switches SW1-1, SW1-2, SW2-1, SW2-2, and a control circuit U1b.

[0061] Each of capacitors C1-1 and C1-2 has one electrode connected to the connection point Nu between IGBT30 and IGBT40, which is connected in series with IGBT30. The other electrode of each capacitor is connected to the cathode of diode D1 via switches SW1-1 and SW1-2. That is, the reference voltage for capacitors C1-1 and C1-2 is voltage Vu. Capacitor C1-1 corresponds to the "first capacitor," capacitor C1-2 corresponds to the "third capacitor," one electrode of capacitor C1-2 corresponds to the "fifth electrode," and the other electrode of capacitor C1-2 corresponds to the "sixth electrode." Switch SW1-1 corresponds to the "first switch," and switch SW1-2 corresponds to the "third switch."

[0062] Switches SW2-1 and SW2-2 are connected in parallel with capacitors C1-1 and C1-2, respectively, in order to discharge them. That is, each switch SW2-1 and SW2-2 is positioned between the other electrode of capacitors C1-1 and C1-2 and the connection point Nu.

[0063] The control circuit U1b turns on at least one of switches SW1-1 and SW1-2 when the conversion circuit 103 outputs the signal DATA and it is time to start communication with the lower arm receiving unit 230, that is, during the communication period when IGBT 30 turns off and IGBT 40 turns on. In other words, as will be described in detail later, when it is time to start communication and the voltage Vu becomes the ground voltage, the control circuit U1b turns on at least one of switches SW1-1 and SW1-2.

[0064] Then, when IGBT30 is turned on and IGBT40 is turned off, control circuit U1b turns on switches SW2-1 and SW2-2, discharging the charge stored in capacitors C1-1 and C1-2. In other words, as will be explained in detail later, when the voltage Vu of control circuit U1b becomes the power supply voltage Vcc, switches SW2-1 and SW2-2 are turned on. Note that the voltage Vu at connection point Nu is applied to terminal gnd of control circuit U1b, and the voltage of power supply V2, referenced to connection point Nu, is applied to terminal vdd.

[0065] ==Configuration of the lower arm receiving unit 230== The lower arm receiving unit 230 receives information from the upper arm transmitting unit 104. The lower arm receiving unit 230 is composed of a capacitor C2, a charging circuit 300, and a signal output circuit 302.

[0066] The signal output circuit 302 causes the charging circuit 300 to charge capacitor C2 and outputs signals Sout_X1 and Sout_X2 corresponding to the charging voltage of capacitor C2. Specifically, the signal output circuit 302 causes the charging circuit 300 to charge capacitor C2 when IGBT 30 is ON and IGBT 40 is OFF. Also, when IGBT 30 is OFF and IGBT 40 is ON, the signal output circuit 302 outputs signals Sout_X1 and Sout_X2 corresponding to the charging voltage of capacitor C2, which changes depending on whether or not charge has moved from capacitor C2 to capacitors C1-1 and C1-2 via diode D1. The signal output circuit 302 is composed of a control circuit U2b and comparators U3-1 and U3-2.

[0067] When IGBT30 is ON and IGBT40 is OFF, control circuit U2b turns on switch SW3 to charge capacitor C2 in the charging circuit 300. Control circuit U2b also outputs signal Sout_X1 according to the logic level of signal comp_o1 from comparator U3-1, and signal Sout_X2 according to the logic level of signal comp_o2 from comparator U3-2.

[0068] Comparator U3-1 compares the charging voltage V_C2 of capacitor C2 with a reference voltage Vref1-1. Comparator U3-2 also compares the charging voltage V_C2 of capacitor C2 with a reference voltage Vref1-2. Specifically, comparators U3-1 and U3-2 output "H" level signals comp_o1 and comp_o2 if the charging voltage V_C2 of capacitor C2 is equal to voltage V1 and higher than the reference voltages VREF1-1 and VREF1-2.

[0069] On the other hand, comparator U3-1 outputs a "L" level signal comp_o1 when the charge stored in capacitor C2 is transferred to capacitors C1-1 and C1-2 via diode D1, causing the charging voltage V_C2 of capacitor C2 to be lower than the reference voltage Vref1-1, and outputs a "H" level signal comp_o1 when the charging voltage V_C2 of capacitor C2 is higher than the reference voltage Vref1-1.

[0070] Furthermore, comparator U3-2 outputs a "L" level signal comp_o2 when the charge stored in capacitor C2 is transferred to capacitors C1-1 and C1-2 via diode D1, and the charging voltage V_C2 of capacitor C2 is lower than the reference voltage Vref1-2. It also outputs a "H" level signal comp_o2 when the charging voltage V_C2 of capacitor C2 is higher than the reference voltage Vref1-2.

[0071] As a result, information indicating the temperature of the IGBT30 detected in HVIC20b is communicated from HVIC20b to LVIC23b. Therefore, it is possible to provide a communication circuit that can communicate information between circuits with different reference voltages.

[0072] Furthermore, if the capacitance values ​​of capacitors C1-1 and C1-2 are the same, the charging voltage V_C2 of capacitor C2 changes in three ways depending on the on / off combination of SW1-1 and SW1-2. Therefore, the combination of signals Sout_X1 and Sout_X2 changes in three ways depending on the level of the charging voltage V_C2. Thus, by associating these three patterns as shown in Figure 10, it is possible to output three types of information to the outside based on the signal DATA for each timing when IGBT30 is off and IGBT40 is on. This makes it possible to communicate multi-bit information corresponding to the signal DATA to the outside. Also, the information corresponding to the patterns may be different from that in this embodiment.

[0073] Furthermore, if the capacitance values ​​of capacitors C1-1 and C1-2 are different, the voltage V_C2 across capacitor C2 changes in four ways depending on the on / off combination of SW1-1 and SW1-2. Therefore, by using three comparators, the combination of signals Sout_X1 and Sout_X2 can be changed in four ways depending on the level of the charging voltage of voltage V_C2.

[0074] <<<Third Embodiment>>> Figure 11 shows an example of the configuration of HVIC20c, which is one embodiment of HVIC20. HVIC20c drives the IGBT30 based on the drive signal SinU from the microcontroller 11. Furthermore, HVIC20c communicates information to the outside via the terminal Sout_U. HVIC20c is composed of a drive circuit 100, an upper arm receiving unit 105, and terminals IN, OUT, DI_IN, Sout_U, and GND.

[0075] The upper arm receiver 105, as will be described in detail later, communicates information indicating an abnormality in IGBT40 from LVIC23c. The cathode of diode D1 (see Figure 2) is connected to terminal DI_IN, and the voltage Vu of the connection point Nu, which varies depending on the on / off state of IGBT30 and 40, is applied to terminal GND.

[0076] ==LVIC23c== Figure 12 shows an example of the configuration of LVIC23c, which is one embodiment of LVIC23. LVIC23c drives IGBTs 40, 43, and 46 based on drive signals SinX, SinY, and SinZ from the microcontroller 11. Furthermore, LVIC23c communicates information to the upper arm receiving units 105 included in HVIC20c, HVIC21c, and HVIC22c, respectively, via diodes D1 to D3.

[0077] The LVIC23c consists of drive circuits 200-202, lower arm transmitters 240-242, detection circuit 250, and terminals IN_X, IN_Y, IN_Z, OUT_X, OUT_Y, OUT_Z, DI_X, DI_Y, DI_Z, tmp_XA, tmp_XC, tmp_YA, tmp_YC, tmp_ZA, tmp_ZC, and GND.

[0078] The lower arm transmitters 240-242 communicate information to the upper arm receiver 105 of the HVIC20c, 21c, and 22c, as will be described in detail later. A ground voltage is applied to the GND terminal.

[0079] The detection circuit 250 supplies a predetermined current to diodes 42, 45, and 48 from terminals tmp_XA, tmp_YA, and tmp_ZA, respectively. The detection circuit 250 then detects the forward voltage VF of diodes 42, 45, and 48 that occurs between terminals tmp_XA and tmp_XC, between terminals tmp_YA and tmp_YC, and between terminals tmp_ZA and tmp_ZC, respectively. When each forward voltage VF falls below a predetermined level, the detection circuit 250 outputs signals DETX, DETY, and DETZ, respectively, indicating overheating of IGBTs 40, 43, and 46.

[0080] ==Configuration of the upper arm receiving unit 105== Figure 13 shows an example of the configuration of the upper arm receiver 105 included in HVIC20c and the lower arm transmitter 240 included in LVIC23c. The upper arm receiver 105, the lower arm transmitter 240, and diode D1 constitute the communication circuit 17.

[0081] The upper arm receiving unit 105 receives information indicating overheating of the IGBT 40 from the lower arm transmitting unit 240. The upper arm receiving unit 105 is composed of a capacitor C1, a switch SW2, and a signal output circuit 400.

[0082] Capacitor C1 has one electrode connected to the connection point Nu between IGBT30 and IGBT40, which is connected in series with IGBT30, and the cathode of diode D1 is connected to the other electrode. In other words, the reference voltage for capacitor C1 is the voltage Vu. Note that capacitor C1 corresponds to the "first capacitor," one electrode of capacitor C1 corresponds to the "first electrode," and the other electrode of capacitor C1 corresponds to the "second electrode."

[0083] Switch SW2 is connected in parallel with capacitor C1 to discharge capacitor C1; that is, switch SW2 is located between the other electrode of capacitor C1 and the connection point Nu.

[0084] Furthermore, switch SW2 is turned on when IGBT30 is turned on and IGBT40 is turned off, and it discharges the charge stored in capacitor C1. In other words, switch SW2 is turned on when the voltage Vu becomes the power supply voltage Vcc. Note that switch SW2 corresponds to the "second switch".

[0085] The signal output circuit 400 turns switch SW2 on and off and outputs a signal Sout_U corresponding to the charging voltage of capacitor C1. Specifically, the signal output circuit 400 turns switch SW2 on when IGBT30 is on and IGBT40 is off. Also, when IGBT30 is off and IGBT40 is on, the signal output circuit 400 turns switch SW2 off and outputs a signal Sout_U corresponding to the charging voltage of capacitor C1, which changes depending on whether or not charge has moved from capacitor C2 (described later) to capacitor C1 via diode D1. The signal output circuit 400 is composed of a control circuit U1c and a comparator U4. The signal output circuit 400 corresponds to the "second signal output circuit".

[0086] When IGBT30 is ON and IGBT40 is OFF, control circuit U1c turns on switch SW2 and discharges the charge from capacitor C1. Then, when IGBT30 is OFF and IGBT40 is ON, control circuit U1c communicates a signal Sout_U to the outside, corresponding to the logic level of the output signal of comparator U4. Note that the voltage Vu at the connection point Nu of IGBT30 and IGBT40 is applied to terminal gnd of control circuit U1c, and the voltage V2 of power supply V2, which is referenced to the voltage Vu at connection point Nu, is applied to terminal vdd.

[0087] Comparator U4 compares the charging voltage of capacitor C1 with a reference voltage Vref. Specifically, when charge moves from capacitor C2 to capacitor C1 via diode D1, and the charging voltage of capacitor C1 becomes higher than the reference voltage Vref, comparator U4 outputs an "H" level output signal. On the other hand, when capacitor C1 is discharged and has no charge, comparator U4 outputs an "L" level output signal.

[0088] ==Configuration of the lower arm transmitter unit 240== The lower arm transmitter 240 transmits information to the upper arm receiver 105. The lower arm transmitter 240 includes a capacitor C2 and a charging circuit 303.

[0089] Capacitor C2 has a ground voltage applied to one electrode, and the anode of diode D1 is connected to the other electrode. Capacitor C2 corresponds to the "second capacitor," one electrode of capacitor C2 corresponds to the "third electrode," and the other electrode of capacitor C2 corresponds to the "fourth electrode."

[0090] The charging circuit 303 is a circuit that charges capacitor C2, and charges capacitor C2 when communication starts, that is, during the communication period, when IGBT 30 is ON and IGBT 40 is OFF. The charging circuit 303 consists of a switch SW3, a power supply V1, and a control circuit U2c.

[0091] Switch SW3 is turned on when charging capacitor C2. Specifically, switch SW3 is turned on when IGBT30 is on and IGBT40 is off. When switch SW2 is turned on, capacitor C2 is charged by the voltage V1 of power supply V1. On the other hand, switch SW3 is turned off when IGBT30 is off and IGBT40 is on.

[0092] Control circuit U2c turns on switch SW3 when detection circuit 250 outputs signal DETX, IGBT30 is on and IGBT40 is off. If detection circuit 250 does not output signal DETX, switch SW3 is off when IGBT30 is on and IGBT40 is off. Signal output circuit 301 also turns off switch SW3 when IGBT30 is off and IGBT40 is on. As a result, if capacitor C2 is charged, charge moves from capacitor C2 to capacitor C1 via diode D1.

[0093] As a result, information indicating an abnormality in IGBT40 detected by LVIC23c is communicated from LVIC23c to HVIC20c. Therefore, it is possible to provide a communication circuit that can transmit information between circuits with different reference voltages.

[0094] =====Summary===== The semiconductor module 10, which is one embodiment of the present invention, has been described above. The communication circuit 15 includes a capacitor C1, a capacitor C2, a diode D1, a switch SW1, and a charging circuit 300. Switch SW1 is turned on when communicating information from HVIC20a to LVIC23a. When switch SW1 is turned on, IGBT30 is turned off, and when IGBT40 is on, charge is transferred from capacitor C2, which is pre-charged by the charging circuit 300, to capacitor C1. This makes it possible to provide a communication circuit that can communicate information between circuits with different reference voltages.

[0095] Furthermore, the communication circuit 15 includes a signal output circuit 301. This allows the signal Sout_X to be output to the microcontroller 11 according to the charging voltage V_C2 of the capacitor C2.

[0096] Furthermore, the communication circuit 15 includes a control circuit U1a. This allows the control circuit U1a to turn the switch SW1 on and off, enabling it to communicate any abnormalities occurring in the IGBT 30 from the HVIC 20a to the LVIC 23a.

[0097] Furthermore, the communication circuit 15 includes a switch SW2. This allows the control circuit U1a to turn the switch SW2 on and off, discharge the charge that has moved to the capacitor C1, and communicate information to set the level of the charge voltage V_C2 of the discharged capacitor C2 to a predetermined level.

[0098] Furthermore, the communication circuit 16 includes a capacitor C1-2 and a switch SW1-2. By switching the switches SW1-1 and SW1-2 on and off, the charging voltage of the capacitor C2 can be changed in four different ways.

[0099] Furthermore, the communication circuits 15 and 16 control the switch SW1 based on the forward voltage VF of the diode 32. This allows the communication circuits 15 and 16 to communicate information indicating overheating of the IGBT 30 to the LVIC 23a and 23b.

[0100] Furthermore, diode D1 has a voltage rating higher than the power supply voltage Vcc (e.g., 400V) applied to IGBT30. This allows for lower-cost communication of information between, for example, HVIC20 and LVIC23 than by providing a high-voltage transistor within the integrated circuit.

[0101] Furthermore, the communication circuit 17 includes capacitor C1, capacitor C2, diode D1, and charging circuit 303. This enables information to be communicated from LVIC23c to HVIC20c.

[0102] Furthermore, the communication circuit 17 includes a signal output circuit 400. This allows the signal Sout_U to be output externally according to the charging voltage of capacitor C1.

[0103] Furthermore, the communication circuit 17 includes a switch SW2. This allows the control circuit U1c to turn the switch SW2 on and off, discharge the charge that has moved to the capacitor C1, and communicate information to set the level of the charging voltage of the charging capacitor C1 to a predetermined level.

[0104] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. Furthermore, the present invention may be modified or improved without departing from its spirit, and it goes without saying that equivalents thereof are included. [Explanation of Symbols]

[0105] 1. Motor drive unit 10 Semiconductor Modules 11 Microcontroller 12 3-phase motor 15, 16, 17 Communication circuits 20,20a,20b,20c,21,21a,21b,21c,22,22a,22b,22c HVIC 23,23a,23b,23c LVIC 30, 33, 36, 40, 43, 46 IGBT 31, 34, 37, 41, 44, 47 Freewheeling diodes 32, 35, 38, 42, 45, 48 diodes 100, 200~202 Drive Circuit 101,250 detection circuit 102,104 Upper arm transmitter 103 Conversion Circuit 105 Upper arm receiving unit 220~222, 230~232 Lower arm receiving section 240~242 Lower arm transmitter 300,303 Charging circuit 301, 302, 400 Signal Output Circuit

Claims

1. A first switching element on the power supply side, a first capacitor having a first electrode connected in series with the first switching element and connected to the connection point with the second switching element on the ground side, and a second electrode, A second capacitor having a third electrode to which a ground voltage is applied, and a fourth electrode, A diode having an anode connected to the fourth electrode and a cathode, A first switch located between the cathode and the second electrode, A charging circuit that charges the second capacitor when the first switching element is ON and the second switching element is OFF, Equipped with, The first switch is, During a communication period in which an abnormal signal indicating a malfunction of the first switching element is output, when the first switching element is off and the second switching element is on, the following is turned on: Communication circuit.

2. A communication circuit according to claim 1, A first signal output circuit that outputs a signal corresponding to the charging voltage of the second capacitor, A communication circuit equipped with this.

3. A communication circuit according to claim 2, The system includes a switch control circuit located between the aforementioned connection point and a power supply with respect to the aforementioned connection point. The aforementioned switch control circuit is During the aforementioned communication period, when the first switching element turns off and the second switching element turns on, the first switch is turned on. Communication circuit.

4. A communication circuit according to claim 3, A second switch located between the second electrode and the connection point, A communication circuit equipped with this.

5. A communication circuit according to claim 4, A third capacitor having a fifth electrode and a sixth electrode connected to the aforementioned connection point, A third switch located between the cathode and the sixth electrode, Equipped with, The capacitance of the third capacitor is different from that of the first capacitor. The aforementioned switch control circuit is During the aforementioned communication period, when the first switching element turns off and the second switching element turns on, at least one of the first and third switches is turned on. Communication circuit.

6. A communication circuit according to any one of claims 3 to 5, The aforementioned switch control circuit is Based on the temperature detected by the detection element that detects the temperature of the first switching element, at least the first switch is controlled. Communication circuit.

7. A communication circuit according to claim 1, The diode has a breakdown voltage higher than the power supply voltage applied to the first switching element. Communication circuit.

8. A first switching element on the power supply side, a first capacitor having a first electrode connected in series with the first switching element and connected to the connection point with the second switching element on the ground side, and a second electrode, A second capacitor having a third electrode to which a ground voltage is applied, and a fourth electrode, A diode having an anode connected to the fourth electrode and a cathode connected to the second electrode, A charging circuit that charges the second capacitor when the first switching element is on and the second switching element is off during a communication period in which an abnormal signal indicating a malfunction of the first switching element is output, A communication circuit equipped with this.

9. A communication circuit according to claim 8, A second signal output circuit that outputs a signal corresponding to the charging voltage of the first capacitor, A communication circuit equipped with this.

10. A communication circuit according to claim 9, A second switch located between the second electrode and the connection point, A communication circuit equipped with this.

11. The first switching element on the power supply side, The first switching element is connected in series with the second switching element on the ground side, A first drive circuit for driving the first switching element, A second drive circuit for driving the second switching element, A first capacitor having a first electrode and a second electrode connected to the connection point of the first and second switching elements, A second capacitor having a third electrode to which a ground voltage is applied, and a fourth electrode, A diode having an anode connected to the fourth electrode and a cathode, A first switch located between the cathode and the second electrode, A charging circuit that charges the second capacitor when the first switching element is ON and the second switching element is OFF, Equipped with, The first switch is, During a communication period in which an abnormal signal indicating a malfunction of the first switching element is output, when the first switching element is off and the second switching element is on, the following is turned on: Semiconductor module.

Images