Switching element drive circuit

Abstract

To provide a technology that does not require an external circuit for high voltage resistance.SOLUTION: A switching element drive circuit includes a primary circuit and a secondary circuit, and an insulating element that insulates the primary circuit and the secondary circuit from each other regarding direct current. The secondary circuit includes a semiconductor substrate, a detection portion that is provided on a part of the semiconductor substrate, includes a pn junction separation portion, and detects the voltage of the high voltage side terminal, and a control portion that is provided on the remaining part of the semiconductor substrate and controls a control voltage of the semiconductor switching element on the basis of the second signal and the detection result of the detection portion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a switching element drive circuit.

Background Art

[0002] Various techniques have been proposed for a switching element drive circuit that drives a semiconductor switching element. For example, in Patent Document 1, a switching element drive circuit is proposed in which the voltage of a primary side circuit is modulated to generate the voltage of a secondary side circuit, and a low voltage circuit is provided as a detection circuit for detecting the state of a semiconductor switching element in the secondary side circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the prior art, since the detection circuit for detecting the state of the semiconductor switching element is a low voltage circuit of the secondary side circuit, there is a problem that the high voltage state of the semiconductor switching element cannot be detected. Further, in order to solve this problem, if an external circuit for increasing the withstand voltage of the detection circuit is provided, new problems such as an increase in the size and cost of the circuit occur.

[0005] [[ID=:39]]Therefore, the present disclosure has been made in view of the above problems, and an object thereof is to provide a technique that does not require an external circuit for increasing the withstand voltage.

Means for Solving the Problems

[0006] The switching element driving circuit according to this disclosure is a switching element driving circuit for driving a semiconductor switching element having a control terminal and a high-voltage side terminal and a low-voltage side terminal controlled by a control voltage applied to the control terminal, comprising a primary side circuit and a secondary side circuit, and an insulating element that insulates the primary side circuit and the secondary side circuit from each other with respect to DC and generates a second signal of the secondary side circuit based on a first signal of the primary side circuit, wherein the secondary side circuit comprises a semiconductor substrate, a detection unit provided in a part of the semiconductor substrate and including a pn junction isolation unit for detecting the voltage of the high-voltage side terminal, and a control unit provided in the remaining part of the semiconductor substrate for controlling the control voltage of the semiconductor switching element based on the second signal and the detection result of the detection unit, wherein the pn junction isolation unit increases the withstand voltage of the detection unit. The detection unit includes a high-voltage resistor connected to the high-voltage side terminal, a resistor that works in cooperation with the high-voltage resistor to divide the voltage at the high-voltage side terminal, and a comparator that determines whether the voltage at the high-voltage side terminal is abnormal based on the divided voltage, and the pn junction isolation unit is included in the high-voltage resistor. ru. [Effects of the Invention]

[0007] According to this disclosure, the secondary circuit is provided on a part of the semiconductor substrate and includes a pn junction isolation section, and includes a detection section that detects the voltage of the high-voltage side terminal, and a control section provided on the remaining part of the semiconductor substrate that controls the control voltage based on a second signal and the detection result of the detection section. With this configuration, an external circuit for high voltage resistance is not required. [Brief explanation of the drawing]

[0008] [Figure 1] This is a circuit diagram showing the configuration of a switching element drive circuit according to Embodiment 1. [Figure 2] This is a perspective view showing the configuration of the switching element drive circuit according to Embodiment 1. [Figure 3] This is a circuit diagram showing the configuration of the switching element drive circuit according to Embodiment 2. [Figure 4] This is a circuit diagram showing the configuration of the switching element drive circuit according to Embodiment 3. [Figure 5] This is a circuit diagram showing the configuration of a switching element drive circuit according to Embodiment 4. [Figure 6]This is a circuit diagram showing the configuration of the switching element drive circuit according to Embodiment 5. [Figure 7] This is a circuit diagram showing the configuration of the switching element drive circuit according to Embodiment 6. [Modes for carrying out the invention]

[0009] The embodiments will be described below with reference to the attached drawings. The features described in each of the embodiments below are illustrative, and not all features are necessarily required. In addition, in the descriptions below, the same or similar reference numerals are used for similar components in multiple embodiments, and the different components will be described primarily.

[0010] <Embodiment 1> Figures 1 and 2 are a circuit diagram and a perspective view showing the configuration of the switching element driving circuit 51 according to this embodiment 1. The switching element driving circuit 51 is configured to drive a semiconductor switching element 52 via terminal HOUT.

[0011] The semiconductor switching element 52 has a control terminal and high-voltage and low-voltage terminals that are controlled by a control voltage applied to the control terminal. In this embodiment 1, the semiconductor switching element 52 is an IGBT (Insulated Gate Bipolar Transistor), the control terminal is the gate terminal connected to terminal HOUT, the control voltage is the gate voltage, the high-voltage terminal is the collector terminal connected to terminals P and HV, and the low-voltage terminal is the emitter terminal connected to terminals OUT and VS. Note that the semiconductor switching element 52 is not limited to an IGBT, and may be, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or an RC-IGBT (Reverse Conducting - IGBT).

[0012] The material of the semiconductor switching element 52 may be ordinary silicon (Si), or may be a wide-bandgap semiconductor such as silicon carbide (SiC), gallium nitride (GaN), or diamond. When the material of the semiconductor switching element 52 is a wide-bandgap semiconductor, stable operation at high temperatures and high voltages, and an increase in the switching speed are possible.

[0013] The switching element drive circuit 51 drives the semiconductor switching element 52 by controlling the control voltage of the control terminal of the semiconductor switching element 52 via the terminal HOUT. The switching element drive circuit 51 according to the first embodiment includes a primary circuit 1, a secondary circuit 2, and an insulating element (isolator) 3.

[0014] The primary circuit 1 and the secondary circuit 2 are insulated from each other except for the portions related to the insulating element 3. In the first embodiment, as shown in FIG. 2, the primary circuit 1 and the secondary circuit 2 are separately provided on the die pad 4. The primary circuit 1 and the secondary circuit 2 each include semiconductor substrates 1s and 2s, and the semiconductor substrates 1s and 2s are also separately provided on the die pad 4.

[0015] The primary circuit 1 includes the signal generation circuit 1a of FIG. 1 in addition to the semiconductor substrate 1s of FIG. 2. The signal generation circuit 1a generates a first signal of the primary circuit 1 based on the signals of the terminals VCC, HIN, and GND.

[0016] The insulating element 3 insulates the primary circuit 1 and the secondary circuit 2 from each other with respect to direct current. On the other hand, the insulating element 3 does not insulate the primary circuit 1 and the secondary circuit 2 from each other with respect to alternating current, and generates a second signal of the secondary circuit 2 based on the first signal generated by the signal generation circuit 1a. The second signal is the signal between the terminals VB and VS. As will be described later, the insulating element 3 may be, for example, a transformer or a capacitor.

[0017] The secondary-side circuit 2 includes, in addition to the semiconductor substrate 2s in FIG. 2, the high-voltage detection circuit 2a, the protection logic circuit 2b, and the drive circuit 2c in FIG. 1. The high-voltage detection circuit 2a is included in the concept of the detection unit, and the protection logic circuit 2b and the drive circuit 2c are included in the concept of the control unit.

[0018] As shown in FIG. 2, the high-voltage detection circuit 2a is provided in a part of the semiconductor substrate 2s and includes a pn junction isolation part 2a1. The pn junction isolation part 2a1 is, for example, a RESURF region having a pn junction and relaxing an electric field, and is formed by a junction isolation type process technology. By this pn junction isolation part 2a1, a part of the high-voltage detection circuit 2a, that is, a part of the secondary-side circuit 2 is made to have a high withstand voltage. Also, as shown in FIG. 1, the high-voltage detection circuit 2a is connected to the high-voltage side terminal so as to be able to detect the voltage of the high-voltage side terminal of the semiconductor switching element 52 via the terminal HV.

[0019] The protection logic circuit 2b and the drive circuit 2c are provided in the remaining part of the semiconductor substrate 2s. That is, the high-voltage detection circuit 2a, the protection logic circuit 2b, and the drive circuit 2c are monolithically provided on the same semiconductor substrate 2s.

[0020] The protection logic circuit 2b generates a control signal based on the second signal generated by the insulating element 3 and the detection result of the high-voltage detection circuit 2a. The drive circuit 2c controls the control voltage of the semiconductor switching element 52 via the terminal HOUT based on the control signal generated by the protection logic circuit 2b. For example, when the detection result of the high-voltage detection circuit 2a indicates that the voltage of the high-voltage side terminal of the semiconductor switching element 52 is normal, the semiconductor switching element 52 is driven based on the second signal. On the other hand, when the detection result of the high-voltage detection circuit 2a indicates that the voltage of the high-voltage side terminal of the semiconductor switching element 52 is abnormal, the driving of the semiconductor switching element 52 is stopped.

[0021] According to the switching element driving circuit 51 of this embodiment 1 described above, the high-voltage detection circuit 2a is provided on a part of the semiconductor substrate 2s and includes a pn junction isolation section 2a1, while the protection logic circuit 2b and the driving circuit 2c are provided on the remaining part of the semiconductor substrate 2s. In other words, the high-voltage detection circuit 2a, the protection logic circuit 2b and the driving circuit 2c are monolithically provided, and the pn junction isolation section 2a1 makes the high-voltage detection circuit 2a, that is, a part of the secondary circuit 2, highly resistant to voltage, thus eliminating the need for an external circuit for high-voltage protection. This is expected to suppress increases in circuit size and cost.

[0022] <Embodiment 2> Figure 3 is a circuit diagram showing the configuration of a switching element drive circuit 51 according to this second embodiment. In this second embodiment, the insulating element 3 includes a modulation circuit (TX circuit) 3a1 provided in the primary circuit 1, a demodulation circuit (RX circuit) 3a2 provided in the secondary circuit 2, and a coreless circuit 3a3 provided between them. The coreless circuit 3a3 includes a primary coil connected to the modulation circuit 3a1 and a secondary coil connected to the demodulation circuit 3a2.

[0023] The modulation circuit 3a1 modulates the first signal of the primary side circuit 1 and causes an alternating current to flow through the primary side coil, and the demodulation circuit 3a2 demodulates the signal to the second signal of the secondary side circuit 2 based on the alternating current generated in the secondary side coil which is magnetically coupled with the primary side coil. The other configurations are the same as those of the first embodiment.

[0024] According to the switching element drive circuit 51 of this embodiment 2 described above, the insulating element 3 includes a coreless 3a3, so a magnetic coupling method is used for signal transmission from the primary circuit 1 to the secondary circuit 2. As a result, an improvement in the CMTI (i.e., dV / dt withstand voltage) characteristics of the semiconductor switching element 52 can be expected.

[0025] <Embodiment 3> Figure 4 is a circuit diagram showing the configuration of a switching element drive circuit 51 according to this third embodiment. In this third embodiment, the insulating element 3 includes a modulation circuit (TX circuit) 3b1 provided in the primary circuit 1, a demodulation circuit (RX circuit) 3b2 provided in the secondary circuit 2, and a capacitor 3b3 provided between them. The capacitor 3b3 includes a first part connected to the modulation circuit 3a1 and a second part connected to the demodulation circuit 3a2.

[0026] The modulation circuit 3b1 modulates the first signal of the primary circuit 1 to generate an electric field in the first part, and the demodulation circuit 3b2 demodulates the electric field generated in the second part, which is capacitively coupled with the first part, to the second signal of the secondary circuit 2. The rest of the configuration is the same as that of Embodiment 1.

[0027] As described above, with the switching element drive circuit 51 according to this second embodiment, the insulating element 3 includes a capacitor 3b3, so a capacitive coupling method is used for signal transmission from the primary circuit 1 to the secondary circuit 2. This makes it possible to easily and inexpensively increase the thickness of the capacitor 3b3, that is, the distance between the first and second parts, so that high voltage resistance of the circuit can be achieved inexpensively and easily depending on the application.

[0028] <Embodiment 4> Figure 5 is a circuit diagram showing the configuration of the switching element drive circuit 51 according to this embodiment 4. In this embodiment 4, the high voltage detection circuit 2a includes a DeSAT circuit. The other configurations are the same as those in embodiment 1.

[0029] In the example shown in Figure 5, the desat circuit includes a switch 2a2, a constant current circuit 2a3, a circuit 2a4, a high-voltage NchMOSFET 2a5, a circuit 2a6, a high-voltage PchMOSFET 2a7, a signal conversion circuit 2a8, and a comparator 2a9. Circuit 2a4 is included in the cascode current mirror circuit, and circuit 2a6 is included in the Wilson current mirror circuit. The pn junction isolation section 2a1, which increases the withstand voltage of the high-voltage detection circuit 2a, is included in the high-voltage NchMOSFET 2a5 and the high-voltage PchMOSFET 2a7, respectively.

[0030] At a detection timing synchronized with the drive timing of the semiconductor switching element 52, the switch 2a2 is opened, and the constant current from the constant current circuit 2a3 flows to the circuit 2a4 and the high-voltage NchMOSFET 2a5. Only when the voltage (VCE) between the high-voltage side terminal and the low-voltage side terminal of the semiconductor switching element 52 is above a certain voltage, the constant current from the constant current circuit 2a3 is transmitted to the signal conversion circuit 2a8 via the circuit 2a6 and the high-voltage PchMOSFET 2a7. The signal conversion circuit 2a8 converts the transmitted constant current signal into a voltage signal, and the comparator 2a9 transmits a signal to the protection logic circuit 2b if the voltage signal obtained by the signal conversion circuit 2a8 is above a certain voltage level. The desatt circuit configured as described above outputs a detection result to the protection logic circuit 2b indicating that the voltage at the high-voltage side terminal of the semiconductor switching element 52 is abnormal when the voltage at the high-voltage side terminal is above a certain voltage.

[0031] As described above, with the switching element drive circuit 51 according to Embodiment 4, the high-voltage detection circuit 2a includes the desaturation circuit, so the voltage at the high-voltage side terminal of the semiconductor switching element 52 can be directly monitored via terminal HV. Furthermore, according to Embodiment 4, since the detection timing can be synchronized with the drive timing, a blanking time to remove noise during the switching transition period of the semiconductor switching element 52 is unnecessary. This eliminates the need for circuits such as those for the short-circuit withstand capability of the semiconductor switching element 52, thus simplifying the design. In addition, since the pn junction isolation section 2a1 is included in both the high-voltage NchMOSFET 2a5 and the high-voltage PchMOSFET 2a7, an external circuit for high voltage withstand capability is unnecessary, similar to Embodiment 1.

[0032] <Embodiment 5> Figure 6 is a circuit diagram showing the configuration of the switching element drive circuit 51 according to this embodiment 5. In this embodiment 5, the high voltage detection circuit 2a includes a level detection circuit. The other configurations are the same as those in embodiment 1.

[0033] In the example shown in Figure 6, the level detection circuit includes a high-voltage resistor 2a10, a resistor 2a11, and a comparator 2a12. The pn junction isolation section 2a1, which increases the voltage rating of the high-voltage detection circuit 2a, is included in the high-voltage resistor 2a10.

[0034] The high-voltage resistors 2a10 and 2a11 divide the voltage at the high-voltage terminal of the semiconductor switching element 52, converting it into a voltage signal lower than that voltage. The comparator 2a9 transmits a signal to the protection logic circuit 2b when the voltage signal obtained by the high-voltage resistors 2a10 and 2a11 is above a certain voltage level. The level detection circuit configured as described above outputs a detection result to the protection logic circuit 2b indicating that the voltage at the high-voltage terminal of the semiconductor switching element 52 is abnormal when the voltage at the high-voltage terminal is above a certain voltage level.

[0035] As described above, with the switching element drive circuit 51 according to this embodiment 5, the high voltage detection circuit 2a includes the level detection circuit, so the voltage at the high voltage side terminal of the semiconductor switching element 52 can be monitored continuously and directly via terminal HV. Furthermore, since the pn junction isolation section 2a1 is included in the high-voltage resistor 2a10, an external circuit for high voltage resistance is not required, similar to embodiment 1.

[0036] <Embodiment 6> Figure 7 is a circuit diagram showing the configuration of the switching element drive circuit 51 according to this embodiment 6. In this embodiment 6, the semiconductor switching element 52 is a SiC-MOSFET. The other configurations are the same as those in embodiment 1.

[0037] SiC-MOSFETs are relatively expensive. Furthermore, due to the low short-circuit withstand capability of SiC-MOSFETs, setting the protection level in the secondary circuit 2 protecting the SiC-MOSFETs is considered difficult. In contrast, the switching element drive circuit 51 described above can implement, for example, a desat circuit as described in Embodiment 4, which has a short-circuit protection function without being an external component, as the high-voltage detection circuit 2a. Therefore, the overall cost can be reduced, and the design difficulties related to short-circuit withstand capability can be alleviated.

[0038] Furthermore, it is possible to freely combine each embodiment and each variation, and to modify or omit each embodiment and each variation as appropriate.

[0039] The various aspects of this disclosure are summarized below as an appendix.

[0040] (Note 1) A switching element drive circuit for driving a semiconductor switching element having a control terminal and a high-voltage side terminal and a low-voltage side terminal controlled by a control voltage applied to the control terminal, Primary circuit and secondary circuit, An insulating element that isolates the primary circuit and the secondary circuit from each other with respect to DC, and generates a second signal for the secondary circuit based on a first signal for the primary circuit. Equipped with, The aforementioned secondary circuit is Semiconductor substrate and A detection unit is provided on a part of the semiconductor substrate, including a pn junction isolation portion, and detects the voltage of the high-voltage side terminal, A control unit is provided on the remaining portion of the semiconductor substrate, which controls the control voltage of the semiconductor switching element based on the second signal and the detection result of the detection unit. A switching element drive circuit, including the above.

[0041] (Note 2) The insulating element is a switching element drive circuit as described in Appendix 1, including a transformer.

[0042] (Note 3) The insulating element is a switching element drive circuit as described in Appendix 1, which includes a capacitor.

[0043] (Note 4) The detection unit is a switching element driving circuit according to any one of the appendices 1 to 3, including a desat circuit.

[0044] (Note 5) The detection unit is a switching element driving circuit according to any one of the appendices 1 to 3, including a level detection circuit.

[0045] (Note 6) The semiconductor switching element is a SiC-MOSFET, and the switching element driving circuit is as described in any one of the appendices 1 to 5. [Explanation of symbols]

[0046] 1 Primary circuit, 2 Secondary circuit, 2a High voltage detection circuit, 2a1 PN junction isolation section, 2b Protection logic circuit, 2c Drive circuit, 2s Semiconductor substrate, 3 Insulating element, 3a3 Coreless, 3b3 Capacitor, 51 Switching element drive circuit, 52 Semiconductor switching element.

Claims

1. A switching element drive circuit for driving a semiconductor switching element having a control terminal and a high-voltage side terminal and a low-voltage side terminal controlled by a control voltage applied to the control terminal, Primary circuit and secondary circuit, With respect to DC, the primary circuit and the secondary circuit are isolated from each other, and an insulating element generates a second signal in the secondary circuit based on a first signal in the primary circuit. Equipped with, The aforementioned secondary circuit is Semiconductor substrate and A detection unit is provided on a part of the semiconductor substrate, including a pn junction separation portion, and detects the voltage of the high-voltage side terminal, A control unit is provided on the remaining portion of the semiconductor substrate and controls the control voltage of the semiconductor switching element based on the second signal and the detection result of the detection unit. Includes, The pn junction separation section increases the pressure resistance of the detection section. The detection unit is The system includes a high-voltage resistor connected to the high-voltage terminal, a resistor that works in cooperation with the high-voltage resistor to divide the voltage at the high-voltage terminal, and a comparator that determines whether the voltage at the high-voltage terminal is abnormal based on the divided voltage. The pn junction separation portion is included in the high-voltage resistor and is part of the switching element drive circuit.

2. A switching element driving circuit according to claim 1, The aforementioned insulating element is a switching element drive circuit including a transformer.

3. A switching element driving circuit according to claim 1, The insulating element is a switching element drive circuit including a capacitor.

4. A switching element driving circuit according to any one of claims 1 to 3, The detection unit includes a switching element drive circuit, which also includes a desassination circuit.

5. A switching element driving circuit according to any one of claims 1 to 3, The detection unit includes a switching element drive circuit, which also includes a level detection circuit.

6. A switching element driving circuit according to claim 4, The aforementioned semiconductor switching element is a SiC-MOSFET, and the switching element driving circuit is also described.

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