JP2018078533A - Power module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a switching loss and initial fluctuation in a surge voltage, and further, to reduce temperature variation in a total loss consisting of the switching loss and a conduction loss.SOLUTION: A power module 10 comprises a power semiconductor element 43, constant current circuits 20 and 30, switches 41 and 42, and temperature compensation circuits 51, 52, and 53. The constant current circuit 20 injects a constant control drive current I41 corresponding to a reference voltage Vtr to an input capacitance of the power semiconductor element 43 via the switch 41. The constant current circuit 30 discharges a constant control drive current I42 corresponding to a reference voltage Vtf from the input capacitance of the power semiconductor element 43 to the ground side via the switch 42. The temperature compensation circuits 51, 52, and 53 vary the reference voltages Vtr and Vtf depending on an operation temperature of the power semiconductor element 43.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power module in which power elements and the like are accommodated in one package.

  Examples of power semiconductor elements constituting the power module include a power MOSFET (hereinafter simply referred to as “power MOS”), an insulation-controlled bipolar transistor (hereinafter referred to as “IGBT”), a gallium nitride (GaN) power device, and carbonized carbon. Power transistors such as silicon (SiC) power devices are known.

  Patent Document 1 describes a technology of a semiconductor device with a current detection function that can accurately detect a current flowing through an inductive load in a semiconductor device that uses an IGBT to drive and control an inductive load such as an AC motor. ing.

  Patent Document 2 discloses a constant current source, a switching circuit, and a current mode selection circuit that use a current mirror to reduce current consumption in a drive circuit as a power module using, for example, an IGBT as an insulated gate switching element. The technology of a drive circuit having

FIG. 5 is an equivalent circuit diagram showing an outline of a conventional N-channel power MOS.
The N-channel power MOS 1 has three electrodes: a gate G, a drain D, and a source S. For example, a load resistor Rl on the load circuit 6 side and a power supply E that outputs a power supply voltage Vdd are connected in series to the drain and source of the N-channel power MOS1. In this N-channel power MOS1, when the gate voltage Vg applied to the gate G rises and exceeds the threshold voltage Vth, the drain-source is turned on, and when the gate voltage Vg falls and falls below the threshold voltage Vth, The drain-source is turned off.

  The gate G, drain D, and source S have parasitic capacitance, parasitic inductance, and the like. For example, a parasitic capacitance Cgd exists between the gate and the drain, a parasitic capacitance Cgs exists between the gate and the source, and a parasitic capacitance Cds exists between the drain and the source. A parasitic inductance Ld exists on the drain D side, and a parasitic inductance Ls exists on the source S side.

It is the parasitic capacitance Cgd between the gate and the drain that greatly affects the switching characteristics. The parasitic capacitance Cgd between the gate and the drain rapidly increases, for example, about 10 times when the drain-source voltage Vds becomes equal to or lower than the gate-source voltage Vgs. A relational expression such as the following expression (1) is established for each capacitor of the power MOS 1.
Input capacitance Ciss≈Cgd + Cgs
Feedback capacity Crss≈Cgd
Output capacity Coss≈Cgd + Cds (1)

  Since the power MOS 1 is a voltage-controlled element, it does not require a drive current when it is kept in an on state or an off state. However, every time a switching operation is performed, a charge / discharge current is applied to the input capacitance Ciss. Flowing.

FIG. 6 is a switching operation waveform diagram of the power MOS 1 with respect to the load resistor Rl of FIG.
In the power MOS 1 of FIG. 5, when the drain-source voltage Vds falls from a high (hereinafter referred to as “H”) level to a low (hereinafter referred to as “L”) level (that is, the drain current Id changes from the L level to the H level). When the drain-source voltage Vds rises from the L level to the H level (that is, when the drain current Id falls from the H level to the L level), it turns off.

  Here, the turn-on time tr is the time between 90% of the falling waveform of the drain-source voltage Vds and the time of 10% before the falling end. Further, the turn-off time tf is a time between a time of 10% from the start of the rise and a time of 90% before the end of the rise in the rising waveform of the drain-source voltage Vds.

  The hatching region at the intersection of the falling of the drain-source voltage Vds and the rising of the drain current Id and the hatching region at the intersection of the rising of the drain-source voltage Vds and the falling of the drain current Id are on. This is a switching loss Sloss (= Vds × Id) that occurs at the time of switching off / off. When the drain-source voltage Vds rises, an overvoltage surge voltage Vdsg [= (Ld + Ls) × di / dt, where di / dt is a switching time] may occur due to the influence of the parasitic inductances Ld and Ls.

  FIG. 7 is a data sheet diagram showing an example of electrical and thermal characteristics (case temperature Tc = 25 ° C.) of the power MOS 1 of FIG. The case temperature Tc is the temperature of a case that is a package that houses the power MOS 1.

  In FIG. 7, the drain-source on-resistance Ron has a standard value TYP = 6.9 mΩ and a maximum value MAX = 8.7 mΩ as standard values when the drain current Id = 25 A and the gate-source voltage Vgs = 10 V. is there. As for the gate threshold voltage Vth, when the drain current Id = 1 mA and the drain-source voltage Vds = 10 V, the standard value is the minimum value MIN = 2.0 V, the standard value TYP = 3.0 V, and the maximum value MAX = 4.0 V. It is.

  When the drain-source voltage Vds = 25 V, the gate-source voltage Vgs = 0 V, and the operating frequency f = 1 MHz, the input capacitance Ciss is the standard value TYP = 5880 pF, and the feedback capacitance Crss is the standard value. The standard value TYP = 250 pF, and the output capacitance Coss is the standard value TYP = 530 pF.

  Also, drain current Id = 25A, load resistance Rl = 2Ω, power supply voltage Vdd = 50V, gate resistance Rg = 0Ω, (+) side gate-source voltage Vgs (+) = 10V, and (−) side gate-source When the inter-voltage Vgs (−) = 0V, the turn-on time tr is a standard value TYP = 28 ns as a standard value, and the turn-off time tf is a standard value TYP = 49 ns as a standard value.

JP 2003-299363 A International Publication WO2012-153659

  Conventional power modules using power semiconductor elements such as the power MOS 1 have the following problems (a) and (b).

  (A) When only the standard value TYP is defined as the standard value of the turn-on time tr and the turn-off time tf in the data sheet of FIG. 7 showing the electrical and thermal characteristics of the power MOS 1 (for example, the standard of the turn-on time tr) The value TYP is 28 ns, the standard value TYP of the turn-off time tf is 49 ns), and there is no standard value of the maximum value MAX / minimum value MIN in the device design, so the worst (worst) design of the module cannot be performed. That is, in the switching operation waveform of FIG. 6, the worst values of the switching loss Sloss (= Vds × Id) and the surge voltage Vdsg [= (Ld + Ls) × di / dt] are not known.

  Even if the maximum value MAX / minimum value MIN of the turn-on time tr / turn-off time tf can be normalized, the standard value TYP (for example, tr = 28 ns, tf = 49 ns), the maximum value MAX / minimum value MIN is in the range of −50% / + 100%. If the value is used as it is in the design of the power module, the worst value of the switching loss Sloss becomes twice the standard value TYP, and the heat radiation design must be twice as much. Further, regarding the minimum value MIN of the turn-on time tr / turn-off time tf, the surge voltage Vdsg generated by the parasitic inductances Ld and Ls is twice as large as the standard value TYP. There is concern over the deterioration of (Electro-Magnetic Interference noise; EMI noise).

  (B) In the data sheet of FIG. 7, the on-resistance Ron when the power MOS 1 is on (conducting) increases as the case temperature Tc increases due to on / off operation or the like, and decreases as the case temperature Tc decreases. Have. Therefore, when the case temperature Tc is increased by the on / off operation of the power MOS 1, the module loss (that is, the conduction loss) Rloss increases, so that the total loss that is the sum of the switching loss Sloss and the conduction loss Rloss increases. There is.

  The power module of the present invention includes a power semiconductor element, a first constant current circuit, a first switch, a second constant current circuit, a second switch, and a temperature compensation circuit.

  Here, the power semiconductor element includes a first electrode, a second electrode, and a control electrode that performs an on / off operation between the first electrode and the second electrode when a control voltage is applied, The switching element is turned on when a first control drive current is injected into an input capacitance composed of a parasitic capacitance generated in the control electrode, and is turned off when a stored charge of the input capacitance is discharged and a second control drive current is discharged. . The first constant current circuit is a circuit for supplying a constant first control drive current corresponding to an input first reference voltage. The first switch is an on / off operation according to a drive signal, and injects the first control drive current into the input capacitance when the first switch is in an on state.

  The second constant current circuit is a circuit for supplying a constant second control drive current corresponding to the input second reference voltage. The second switch is turned off when the first switch is turned on by the drive signal, and turned on when the first switch is turned off, and the second control drive current is grounded. It is a switch to release. Further, the temperature compensation circuit is a circuit that detects an operating temperature of the power semiconductor element and changes the first reference voltage and / or the second reference voltage according to the temperature detection result.

  The temperature compensation circuit includes, for example, a temperature detection element (for example, a temperature sensing element including a thermistor and a temperature sensing diode) that detects an operating temperature of the power semiconductor element and outputs the temperature detection result, and a temperature detection result. A reference voltage supply circuit that supplies the first reference voltage and / or the second reference voltage that change based on the first reference voltage.

  The reference voltage supply circuit includes, for example, a reference power supply that supplies the first reference voltage and / or the second reference voltage that changes based on the temperature detection result. In addition, the reference voltage supply circuit includes, for example, a voltage dividing resistor connected in series to the temperature detection element to which a power supply voltage is applied.

  The first constant current circuit detects, for example, a first stage or a plurality of stages of a first current mirror circuit that passes the first control drive current proportional to the first drive current and detects the first drive current. And a first error amplification circuit that changes the first drive current by causing the first drive voltage to follow the first reference voltage.

  The second constant current circuit detects, for example, a first stage or a plurality of stages of a second current mirror circuit that passes the second control drive current proportional to the second drive current and detects the second drive current. And a second error amplification circuit 2 that changes the second drive current by causing the second drive voltage to follow the second reference voltage.

  The power module of the present invention has the following effects (A) and (B).

  (A) Since the first constant current circuit and the second constant current circuit are provided, the turn-on time / turn-off can be achieved by adjusting the first reference voltage and / or the second reference voltage according to variations in the power semiconductor elements. The initial variation in the maximum / minimum time can be improved. Thereby, a power module with little variation in switching loss and surge voltage can be realized.

  (B) Since the temperature compensation circuit is provided, the turn-on time / turn-off time is adjusted according to the change in the operating temperature of the power semiconductor element. Thereby, it is possible to realize a power module in which the temperature variation of the total loss (= switching loss + conduction loss) is small.

1 is a schematic circuit diagram showing the principle of a power module in Embodiment 1 of the present invention. 1 is a circuit diagram showing a configuration example of the power module of FIG. 1 in Embodiment 1 of the present invention. Voltage / current waveform diagram showing the operation of the power module 10 of FIG. The equivalent circuit schematic which shows the outline of IGBT as a power semiconductor element in Example 2 of this invention Equivalent circuit diagram showing outline of conventional N-channel type power MOS Switching operation waveform diagram of the power MOS1 with respect to the load resistance Rl of FIG. Data sheet diagram showing an example of the electrical and thermal characteristics (case temperature Tc = 25 ° C.) of the power MOS 1 of FIG.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Configuration of Example 1)
FIG. 1 is a schematic circuit diagram showing the principle of a power module in Embodiment 1 of the present invention.

  The power module 10 includes a package 10a that houses a power semiconductor element and the like. The package 10a is formed of a highly heat-resistant / insulating resin or ceramics. The package 10a includes a (+) side power supply terminal 11a for inputting a DC power supply voltage VDD, a (−) side power supply terminal 11b for grounding, a control terminal 12a for inputting a first DC reference voltage Vtr, and a DC first power supply terminal 11b. 2 a control terminal 12b for inputting a reference voltage Vtf, a control terminal 13 for inputting a drive signal (for example, a gate pulse) Pg, a (+) side output terminal 14a, and a ground side (−) side output terminal 14b. Yes.

  The package 10a accommodates a first constant current circuit 20, a second constant current circuit 30, a first switch 41, a second switch 42, and a power semiconductor element (for example, an N-channel power MOS) 43. The first constant current circuit 20, the first switch 41, the second switch 42, and the second constant current circuit 30 are connected in series between the (+) side power supply terminal 11a and the (−) side power supply terminal 11b. Yes. A gate as a control electrode of the power MOS 43 is connected to a connection point between the first switch 41 and the second switch 42. The drain as the first electrode of the power MOS 43 is connected to the (+) side output terminal 14a, and the source as the second electrode of the power MOS 43 is connected to the (−) side output terminal 14b.

  The first constant current circuit 20 is a circuit that flows a constant first control drive current I41 corresponding to the first reference voltage Vtr input from the control terminal 12a to the first switch 41 side. The first reference voltage Vtr is a voltage for adjusting the turn-on time tr of the power MOS 43. The second constant current circuit 30 is a circuit that flows a constant second control drive current I42 corresponding to the second reference voltage Vtf input from the control terminal 12b to the ground side. The second reference voltage Vtf is a voltage for adjusting the turn-on time tf of the power MOS 43.

  The first switch 41 is turned on / off by the gate pulse Pg input from the control terminal 13 (for example, turned on by the L level of the gate pulse Pg and turned off by the H level). The first control drive current I41 from the one constant current circuit 20 is injected through the gate of the power MOS 43 into the input capacitance Ciss composed of the parasitic capacitance. The second switch 42 is turned off by the gate pulse Pg input from the control terminal 13 when the first switch 41 is turned on (for example, turned off by the L level of the gate pulse Pg). In the off state, it is turned on (for example, turned on by the H level of the gate pulse Pg), and the second control drive current I42 from the gate of the power MOS 43 is discharged to the second constant current circuit 30 side. .

  The power MOS 43 is turned on when the first control drive current I41 is injected into the input capacitance Ciss generated at the gate and the gate voltage Vg as the control voltage applied to the input capacitance Ciss rises and exceeds the threshold voltage Vth, and the input capacitance This is a switching element that is turned off when the accumulated charge of Ciss is discharged and the second control drive current I42 is discharged and the gate voltage Vg applied to the input capacitance Ciss falls and falls below the threshold voltage Vth.

  A gate drive power supply 50 for applying a power supply voltage VDD is connected between the (+) side power supply terminal 11a and the (−) side power supply terminal 11b. A temperature detecting element 51 is provided in the vicinity of the power MOS 43 in the package 10a. The temperature detection element 51 is an element that detects the operating temperature of the power MOS 43 and outputs a temperature detection signal S51 as a temperature detection result. For example, the thermistor that converts the temperature into an electrical quantity and outputs the temperature detection signal S51, It is composed of a temperature sensitive element such as a temperature sensitive diode.

  The temperature detection element 51 is connected to the control terminal 12a via a reference voltage supply circuit (for example, a reference power supply 52 for adjusting a turn-on time (tr)), and other reference voltage supply circuits (for example, a turn-off time (for example, turn-off time (tr)). tf) Connected to the control terminal 12b via the adjustment reference power supply 53). The reference power supply 52 for adjusting the turn-on time (tr) supplies the first reference voltage Vtr that changes based on the temperature detection signal S51. The reference power supply 53 for adjusting the turn-off time (tf) supplies a second reference voltage Vtf that changes based on the temperature detection signal S51. The temperature detecting circuit 51 and the reference power sources 52 and 53 constitute a temperature compensation circuit.

  A load circuit 60 is connected to the (+) side output terminal 14a and the (−) side output terminal 14b. The load circuit 60 includes, for example, a load resistor 61, a DC drive power source 62, and the like, and these are connected in series between the (+) side output terminal 14a and the (−) side output terminal 14b.

FIG. 2 is a circuit diagram illustrating a configuration example of the power module of FIG. 1 according to the first embodiment of the present invention.
In the power module 10 of FIG. 2, the first constant current circuit 20 includes a first stage first current mirror circuit 21 and a first error amplification circuit 22. The first current mirror circuit 21 is a circuit that flows a first control drive current I41 proportional to the first drive current I21a flowing to the input side to the output side. The first error amplifier circuit 22 detects the first drive current I21a flowing to the input side of the first current mirror circuit 21, generates a first drive voltage V22b corresponding to the first drive current I21a, and controls the first drive voltage V22b. In this circuit, the first drive current I21a flowing on the input side of the first current mirror circuit 21 is changed in accordance with the first reference voltage Vtr input from the terminal 12a.

  The first current mirror circuit 21 includes a pair of transistors (eg, P-channel MOSFETs, hereinafter referred to as “PMOS”) 21a and 21b having a transistor size of 1: x (eg, 1: 100). The pair of PMOSs 21a and 21b have their gates connected in common and their sources connected in parallel to the (+) side power supply terminal 11a. The drain of the PMOS 21a is connected to the gates of the PMOSs 21a and 21b.

  The first error amplification circuit 22 detects and responds to a transistor (for example, an N-channel MOSFET, hereinafter referred to as “NMOS”) 22a that changes the current value of the first drive current I21a and the first drive current I21a. And a resistor 22b for generating the first drive voltage V22b and an operational amplifier (hereinafter referred to as "op-amp") 22c. Between the drain of the PMOS 21a, the gates of the PMOS 21a and 21b, and the ground side, the drain / source of the NMOS 22a and the resistor 22b are connected in series. The source of the NMOS 22a is connected to the (−) side input terminal of the operational amplifier 22c, and the gate of the NMOS 22a is connected to the output terminal of the operational amplifier 22c. The operational amplifier 22c has a (+) side input terminal connected to the control terminal 12a, a first drive voltage V22b input to the (−) side input terminal, and a first reference voltage Vtr input to the (+) side input terminal. And has a function of changing the first drive current I21a flowing through the NMOS 22a.

  The second constant current circuit 30 includes a two-stage second current mirror circuit 31 and a second error amplification circuit 32. The second current mirror circuit 31 is a circuit that allows a second control drive current I42 that is proportional to the second drive current I31a flowing on the input side to flow to the output side. The second error amplification circuit 32 detects the second drive current I31a flowing on the input side of the second current mirror circuit 31, generates a second drive voltage V32b corresponding to the second drive current I31a, and controls the second drive voltage V32b. In this circuit, the second drive current I31a flowing to the input side of the second current mirror circuit 31 is changed in accordance with the second reference voltage Vtf input from the terminal 12b.

  The second current mirror circuit 31 includes a pair of first-stage transistors (for example, PMOS) 31a and 31b having a transistor size of 1: 1 and a pair of second-stage transistors having a transistor size of 1: x (for example, 1: 100). Transistors (for example, NMOS) 31c and 31d.

  The PMOSs 31a and 31b on the front stage side have gates connected in common and their sources connected in parallel to the (+) side power supply terminal 11a. The drain of the PMOS 31a is connected to the gates of the PMOS 31a and 31b. The NMOSs 31c and 31d on the rear stage side are connected in common, and the gates are connected to the drain of the PMOS 31b and the drain of the NMOS 31c. The sources of the NMOS 31c and 31d are connected in parallel to the (−) side power supply terminal 11b.

  The second error amplification circuit 32 detects a second drive current I31a by generating a transistor (for example, NMOS) 32a that changes the current value of the second drive current I31a and a second drive voltage V32b corresponding thereto. 32b and an operational amplifier 32c. The drain / source of the NMOS 32a and the resistor 32b are connected in series between the drain of the PMOS 31a, the gates of the PMOS 31a and 31b, and the (−) side power supply terminal 11b on the ground side. The source of the NMOS 32a is connected to the (−) side input terminal of the operational amplifier 32c, and the gate of the NMOS 32a is connected to the output terminal of the operational amplifier 32c. The operational amplifier 32c has a (+) side input terminal connected to the control terminal 12b, a second drive voltage V32b input to the (−) side input terminal, and a second reference voltage Vtf input to the (+) side input terminal. And has a function of changing the second drive current I31a flowing in the NMOS 32a.

  The first switch 41 and the second switch 42 are configured by complementary transistors (for example, CMOS transistors including a PMOS 41a and an NMOS 42a connected in series) that are complementarily turned on / off. The control terminal 13 is connected in common to the gates of the PMOS 41a and the NMOS 42a via the buffer 15. The drain of the PMOS 41 a and the drain of the NMOS 42 a are connected to each other, and this connection point is connected to the gate of the power MOS 43.

  The temperature detection element 51 includes two temperature sensing elements 51a and 51b connected in parallel to the (+) side power supply terminal 11a. The two temperature sensitive elements 51a and 51b are elements that detect the case temperature Tc, which is the temperature of the package 10a, and the size of the temperature sensitive elements 51a and 51b changes according to this temperature detection. At the same time, a negative characteristic (NTC) thermistor whose resistance value decreases is formed.

  The reference power source 52 for adjusting the turn-on time (tr) connected to the one temperature sensing element 51a is constituted by, for example, two voltage dividing resistors 52a and 52b. The temperature sensing element 51a and the two voltage dividing resistors 52a and 52b are connected in series between the (+) side power supply terminal 11a and the (−) side power supply terminal 11b, and the two voltage dividing resistors 52a and 52b are connected. The connection point is connected to the control terminal 12a. Similarly, the reference power supply 53 for adjusting the turn-off time (tf) connected to the other temperature sensing element 51b is constituted by, for example, two voltage dividing resistors 53a and 53b. The temperature sensing element 51b and the two voltage dividing resistors 53a and 53b are connected in series between the (+) side power supply terminal 11a and the (−) side power supply terminal 11b, and the two voltage dividing resistors 53a and 53b are connected. The connection point is connected to the control terminal 12b.

  (Operation of the power module in FIG. 2)

FIG. 3 is a voltage / current waveform diagram showing the operation of the power module 10 of FIG.
3, the horizontal axis represents time t, and the vertical axis represents the voltage value of the source-drain voltage Vds waveform in the power MOS 43 and the current value of the drain current Id waveform in the power MOS 43. Since the electrical and thermal characteristics of the power MOS 43 vary depending on the element, for example, the minimum value tr_min of the turn-on time tr is 50 ns, the maximum value tr_max is 200 ns, and the standard value tr_typ is 100 ns. Similarly, the minimum value tf_min of the turn-off time tf is 50 ns, the maximum value tf_max is 200 ns, and the standard value tf_typ is 100 ns. The hatching region at the intersection of the falling of the drain-source voltage Vds and the rising of the drain current Id and the hatching region at the intersection of the rising of the drain-source voltage Vds and the falling of the drain current Id are on. This is a switching loss Sloss (= Vds × Id) that occurs at the time of switching off / off. When the drain-source voltage Vds rises, an overvoltage surge voltage Vdsg [= (Ld + Ls) × di / dt] may occur due to the influence of the parasitic inductances Ld and Ls.

  For example, when the turn-on time tr and the turn-off time tf are standard values tr_typ (= 50 ns) and tf_typ (= 50 ns) in the standard value of the power MOS 43, the operation is as follows.

  When the gate pulse Pg applied to the control terminal 13 is at L level, it is driven by the buffer 15 and supplied to the gates of the PMOS 41a and NMOS 42a. Then, the PMOS 41a is turned on and the NMOS 42a is turned off.

  The operational amplifier 22c obtains an error between the first reference voltage Vtr applied to the control terminal 12a and the first drive voltage V22b detected by the resistor 22b, and reduces the error (that is, the first drive voltage). The NMOS 22a is gate-controlled so that the V22b follows the first reference voltage Vtr), and the first drive current I21a flowing from the (+) side power supply terminal 11a → the PMOS 21a → the NMOS 22a → the resistor 22b → the ground side is changed. The changed first drive current I21a is amplified, for example, 100 times by the first current mirror circuit 21 including a pair of PMOSs 21a and 21b, and the amplified first control drive current I41 is converted to the (+) side power supply terminal. 11a → source / drain of PMOS 21b → source / drain of PMOS 41a → gate of power MOS 43.

  When the first control drive current I41 flows to the gate of the power MOS 43, the first control drive current I41 is injected into the input capacitor Ciss of the power MOS 43, and the gate voltage Vg of the power MOS 43 rises. When the gate voltage Vg rises and exceeds the threshold voltage Vth of the power MOS 43, the power MOS 43 is turned on after a predetermined turn-on time (standard turn-on time tr_typ = 100 ns). When the power MOS 43 is turned on, a drive current flows from the drive power source 62 in the load circuit 60 to the load resistor 61 to the power MOS 43 to operate the load circuit 60.

  When the gate pulse Pg applied to the control terminal 13 becomes H level, it is driven by the buffer 15, turning off the PMOS 41a and turning on the NMOS 42a.

  The operational amplifier 32c obtains an error between the second reference voltage Vtf applied to the control terminal 12b and the second drive voltage V32b detected by the resistor 32b so that this error is reduced (that is, the second drive voltage). The second drive current flowing from the (+) side power supply terminal 11a → the PMOS 31a → the NMOS 32a → the resistor 32b → the (−) side power supply terminal 11b by controlling the gate of the NMOS 32a so that the V32b follows the second reference voltage Vtf). I31a is changed. The changed second drive current I31a is converted to 1: 1 by the pair of preceding PMOSs 31a and 31b in the second current mirror circuit 31, and then amplified by, for example, 100 times by the pair of subsequent NMOSs 31c and 31d. The second control drive current I42 flows from the gate of the power MOS 43 → the drain / source of the NMOS 42a → the drain / source of the NMOS 31d → the (−) side power supply terminal 11b, and the charge accumulated in the input capacitor Ciss of the power MOS 43 The (−) side power supply terminal 11b is discharged.

  When the electric charge accumulated in the input capacitance Ciss of the power MOS 43 is discharged and the gate voltage Vg drops below the threshold voltage Vth, the power MOS 43 has a predetermined turn-off time (standard turn-off time tf_typ = 100 ns). And turn off. When the power MOS 43 is turned off, the drive current in the load circuit 60 is cut off and the operation stops.

  Next, variations in the power MOS 43 will be described.

  Due to variations in the power MOS 43, the switching loss Sloss (= Vds × Id) and the surge voltage Vdsg [= (Ld + Ls) × di / dt)] vary for each power module 10. Therefore, as an initial state, the first control drive current I41 is adjusted by the first reference voltage Vtr determined by the sizes of the two voltage dividing resistors 52a and 52b and the temperature sensing element 51a, and as shown in FIG. When the turn-on time tr (that is, the falling time of the drain-source voltage Vds) is large, the turn-on time tr is decreased. The second control drive current I42 is adjusted by the second reference voltage Vtf determined by the size of the two voltage dividing resistors 53a and 53b and the temperature sensing element 51b, and the turn-off time tf of the power MOS 43 (that is, the drain-source voltage). When the rise time (Vds) is large, it is decreased, and when the turn-on time tf is small, it is increased. As described above, by setting the optimal first control drive current I41 and second control drive current I42 for each power module 10, it is possible to reduce the initial variation of the switching loss Sloss and the surge voltage Vdsg.

  Finally, the conduction loss Rloss of the power MOS 43 due to temperature change will be described.

  The on-resistance Ron of the power MOS 43 increases as the case temperature Tc, which is the temperature of the package 10a, increases due to an on / off operation or the like, and decreases as the case temperature Tc decreases. Therefore, when the case temperature Tc increases due to the on / off operation of the power MOS1, the conduction loss Rloss increases as shown in FIG. 3, and the total loss, which is the sum of the switching loss Sloss and the conduction loss Rloss, also increases.

  In order to solve this problem, in the first embodiment, the temperature detection element 51 (for example, two temperature sensing elements 51 a and 51 b made of NTC thermistors) is provided in the vicinity of the power MOS 43. When the case temperature Tc is increased by the on / off operation of the power MOS 43, the case temperature Tc is detected by the temperature sensing elements 51a and 51b, and the size of the temperature sensing elements 51a and 51b varies depending on the detected temperature. The first reference voltage Vtr divided by the temperature sensing element 51a and the voltage dividing resistors 52a and 52b changes according to the size of the one temperature sensing element 51a. Furthermore, the second reference voltage Vtf divided by the temperature sensing element 51b and the voltage dividing resistors 53a and 53b changes according to the size of the other temperature sensing element 51b.

  In the first embodiment, when the temperature of the power MOS 43 increases, the reference voltage Vtr / Vtf increases, so that the first control drive current I41 injected into the input capacitor Ciss of the power MOS 43 and the input capacitor Ciss are discharged. The second control drive current I42 is changed, and the turn-on time tr and the turn-off time tf of the drain-source voltage Vds in the power MOS 43 are adjusted. As a result, the switching loss Sloss of the power MOS 43 is reduced, and the total loss, which is the sum of the switching loss Sloss and the conduction loss Rloss, is also less changed than before the temperature is increased.

(Effect of Example 1)
The power module 10 according to the first embodiment has the following effects (1) to (5).

  (1) Since the first constant current circuit 20 and the second constant current circuit 30 are provided, the first reference voltage Vtr and the second reference voltage Vtf are adjusted according to the variation of the power MOS 43, and the turn-on time tr / turn-off The initial variation in the maximum value MAX / minimum value MIN of the time tf is improved. Thereby, the power module 10 with little variation in the switching loss Sloss and the surge voltage Vdsg can be realized.

  (2) Since the temperature compensation circuit including the temperature detecting element 51 and the reference power sources 52 and 53 is provided, the turn-on time tr / turn-off time tf is changed according to the temperature change of the case temperature Tc (that is, the temperature change of the power MOS 43). Adjusted. Thereby, the power module 10 with little temperature fluctuation of the total loss (= switching loss Sloss + conduction loss Rloss) can be realized. Note that the temperature sensitive elements 51a and 51b may be modified to a configuration using a positive characteristic (PTC) thermistor whose resistance value increases as the temperature rises. When the power module 10 is formed as a semiconductor integrated circuit (IC), it is preferable that the temperature sensitive elements 51a and 51b are constituted by temperature sensitive diodes instead of thermistors.

  (3) When the first constant current circuit 20 and the second constant current circuit 30 are configured by, for example, the first and second current mirror circuits 21 and 31, and the first and second error amplification circuits 22 and 32, respectively, The second current mirror circuit 31 may be configured in one stage. Further, if the first current mirror circuit 21 and the second current mirror circuit 31 are multistage (for example, two stages), an increase in current amplification factor and stability of characteristics can be realized.

  (4) For example, when the first reference voltage Vtr and the second reference voltage Vtf are generated by the voltage dividing resistors 52a, 52b, 53a, 53b, the external circuit of the power module 10 can be simplified.

  (5) In the first embodiment, the first reference voltage Vtr and the second reference voltage Vtf are changed. However, either the first reference voltage Vtr or the second reference voltage Vtf is changed. Even if it deform | transforms, the subject of this invention can be solved.

FIG. 4 is an equivalent circuit diagram showing an outline of an IGBT as a power semiconductor element in Example 2 of the present invention.
The IGBT 54 of the second embodiment has three electrodes, ie, an emitter E, a collector C, and a gate G, and has substantially the same effect as the power MOS 43 of the first embodiment.

  In addition, as a power semiconductor element, you may use other power transistors, such as a gallium nitride (GaN) power device and a silicon carbide (SiC) power device.

(Other variations of Examples 1 and 2)
The present invention is not limited to the first and second embodiments, and other forms of use and modifications are possible. For example, the following forms (i) to (iii) are used as the usage form and the modification examples.

  (I) The first and second constant current circuits 20 and 30 may be composed of circuits other than the first and second current mirror circuits 21 and 31 and the first and second error amplification circuits 22 and 32. .

  (Ii) The first and second switches 41 and 42 may be configured using a semiconductor element other than the CMOS transistor including the PMOS 41a and the NMOS 42a.

  (Iii) The temperature sensitive elements 51a and 51b in FIG. 2 may be constituted by elements other than the thermistor and the temperature sensitive diode.

DESCRIPTION OF SYMBOLS 10 Power module 10a Package 20, 30 1st, 2nd constant current circuit 21, 31 1st, 2nd current mirror circuit 22, 32 1st, 2nd error amplification circuit 41, 42 1st, 2nd switch 41a PMOS
42a NMOS
43 Power MOS
51 Temperature detection element 51a, 51b Temperature sensing element 52 Reference power source for adjusting turn-on time (tr) 52a, 52b, 53a, 53b Voltage dividing resistor 53 Reference power source for adjusting turn-off time (tf) 54 IGBT

Claims (8)

A first electrode; a second electrode; and a control electrode that performs on / off operation between the first electrode and the second electrode when a control voltage is applied, and includes a parasitic capacitance generated in the control electrode. A power semiconductor device that is turned on when a first control drive current is injected into an input capacitor, and that is turned off when a charge stored in the input capacitor is discharged and a second control drive current is discharged;
A first constant current circuit for supplying a constant first control drive current corresponding to the input first reference voltage;
A first switch that is turned on / off by a drive signal and injects the first control drive current into the input capacitor when the drive signal is on;
A second constant current circuit for supplying a constant second control drive current corresponding to the input second reference voltage;
A second switch that is turned off when the first switch is turned on by the drive signal, and turned on when the first switch is turned off, and discharges the second control drive current to the ground side; ,
A temperature compensation circuit that detects an operating temperature of the power semiconductor element and changes the first reference voltage and / or the second reference voltage according to the temperature detection result;
A power module comprising: The temperature compensation circuit is:
A temperature detection element that detects an operating temperature of the power semiconductor element and outputs the temperature detection result; and
A reference voltage supply circuit for supplying the first reference voltage and / or the second reference voltage to be changed based on the temperature detection result;
The power module according to claim 1, comprising: The temperature detecting element is
A temperature sensing element including a thermistor that converts the temperature into an electrical quantity and outputs the temperature detection result including an electrical signal and a temperature sensing diode,
The power module according to claim 2. The reference voltage supply circuit includes:
It is constituted by a reference power supply that supplies the first reference voltage and / or the second reference voltage that changes based on the temperature detection result.
The power module according to claim 2 or 3, wherein The reference voltage supply circuit includes:
It is constituted by a voltage dividing resistor connected in series with respect to the temperature detection element to which the power supply voltage is applied.
The power module according to claim 2 or 3, wherein The first constant current circuit includes:
A first stage or a plurality of stages of first current mirror circuits for passing the first control drive current proportional to the first drive current;
A first error amplifying circuit that detects the first drive current, generates a first drive voltage corresponding to the first drive current, and changes the first drive current by causing the first drive voltage to follow the first reference voltage; ,
Have
The second constant current circuit includes:
A one-stage or multiple-stage second current mirror circuit for flowing the second control drive current proportional to the second drive current;
A second error amplification circuit that detects the second drive current, generates a second drive voltage corresponding thereto, and changes the second drive current by causing the second drive voltage to follow the second reference voltage; ,
Having
The power module according to any one of claims 1 to 5, wherein: The first switch and the second switch are:
The power module according to claim 1, wherein the power module is configured by complementary transistors that are complementarily turned on / off by the drive signal. The power semiconductor element is
The power module according to claim 1, which is a power transistor including a power MOSFET, IGBT, GaN power device, and SiC power device.

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