Control circuit and power supply circuit

Abstract

To provide a control circuit capable of further appropriately protecting an element to be protected.SOLUTION: A control circuit 100 comprises a detection value comparison unit 102 that compares a current detection value Vs corresponding to a main current flowing through a power semiconductor 200 with a set current threshold Vsc, a protection unit 120 that suppresses the main current flowing through the power semiconductor 200 when the state in which the current detection value Vs exceeds the current threshold Vsc continues for a period longer than a set duration, and a protection control unit 130 that controls at least one of the current threshold Vsc, the duration, and the rate at which electric charge is extracted from the control terminal based on a control power supply voltage that determines the amplitude of a control signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control circuit and a power supply circuit. [Background technology]

[0002] Patent Document 1 discloses a semiconductor device that "protects a switching element when a sense voltage obtained by converting a sense current obtained by dividing a main current flowing through the switching element into a voltage exceeds a threshold value (Claim 1)." Patent Document 2 discloses a semiconductor device that "detects a main current flowing between main electrodes of a semiconductor device, and protects the semiconductor device when the main current reaches a trip level (Claim 1)." Patent Document 1: JP 2013-77976 A Patent Document 2: JP 2013-62730 A Summary of the Invention [Problem to be solved by the invention]

[0003] It would be desirable to provide better protection for the device being protected. [Means for solving the problem]

[0004] In order to solve the above problem, one aspect of the present invention provides a control circuit for a power semiconductor that operates in response to a control signal applied to a control terminal. The control circuit may include a detection value comparison unit that compares a current detection value corresponding to a main current flowing through the power semiconductor with a set current threshold. Any of the above control circuits may include a protection unit that suppresses the main current flowing through the power semiconductor when a state in which the current detection value exceeds the current threshold continues for a set duration. Any of the above control circuits may include a protection control unit that controls at least one of the current threshold, the duration, and the rate of extraction of charge from the control terminal based on a control power supply voltage that defines the amplitude of the control signal.

[0005] In any of the above control circuits, the protection control unit may control the current threshold value.

[0006] In any of the above control circuits, the protection unit may include a first protection element that suppresses the main current flowing through the power semiconductor when the state in which the current detection value exceeds the current threshold continues for a period longer than a set duration.In any of the above control circuits, the protection unit may include a second protection element that further suppresses the main current flowing through the power semiconductor when the state in which the current detection value exceeds the current threshold continues for a period longer than a set duration and the control power supply voltage exceeds a set voltage threshold.

[0007] Any of the above control circuits may include a set / reset latch that holds and outputs a current comparison result from the detection value comparison unit and sets the output to an initial value when the control signal indicates a logical value that should turn off the power semiconductor. In any of the above control circuits, the protection control unit may output a voltage comparison result between the control power supply voltage and a voltage threshold. In any of the above control circuits, the first protection element may operate according to the output of the set / reset latch. In any of the above control circuits, the second protection element may operate based on the logical product of the output of the set / reset latch and the voltage comparison result.

[0008] Any of the control circuits may include a logical OR circuit that outputs a logical OR of the output of the set-reset latch and the control signal, and a charge / discharge control unit that controls whether to charge the control terminal of the power semiconductor according to the output of the logical OR circuit.

[0009] In any of the above control circuits, the protection control unit may control the duration.

[0010] In any of the above control circuits, the protection control unit may control the extraction speed.

[0011] Any of the control circuits may include an extraction transistor that controls whether the control terminal is connected to a reference potential. In any of the control circuits, the protection control unit may control at least one of a channel area of ​​the extraction transistor and a gate voltage applied to the extraction transistor.

[0012] Any of the control circuits may include a charge / discharge control unit that controls whether to discharge the control terminal of the power semiconductor in response to the control signal. Any of the control circuits may include a discharge resistor provided in a path for discharging the control terminal. In any of the control circuits, the protection control unit may control a resistance value of the discharge resistor.

[0013] In any of the above control circuits, the protection control unit may further control the current threshold. In any of the above control circuits, the protection control unit may control the extraction transistor, whose extraction rate has been changed, to an on state after changing the current threshold.

[0014] In a second aspect of the present invention, there is provided a power supply circuit. The power supply circuit may include the control circuit according to the first aspect. The power supply circuit may include the power semiconductor.

[0015] The above summary of the invention does not list all of the features of the present invention, and subcombinations of these features may also constitute inventions. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram illustrating an example of a control circuit 100 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of a VCC detection circuit 132. [Figure 3] FIG. 2 is a diagram illustrating an example of a filter 110. [Figure 4] FIG. 2 illustrates an example of the configuration of a selection unit 103. [Figure 5] FIG. 4 is a diagram illustrating another example of the configuration of the control circuit 100. [Figure 6] FIG. 10 is a diagram illustrating another example of the operation of the protection control unit 130. [Figure 7] FIG. 10 is a diagram illustrating another example of the operation of the protection control unit 130. [Figure 8] 3 is a diagram illustrating a short-circuit current ISC and short-circuit energy ESC applied to a power semiconductor 200. FIG. [Figure 9] FIG. 1 is a diagram illustrating an example of a power supply circuit 300 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. In this specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to avoid redundant description, and elements not directly related to the present invention are not shown. Furthermore, in a single drawing, elements having the same function and configuration may be designated by the same reference numeral, and the reference numerals may be omitted for other elements.

[0018] In this specification, when we say "same" or "equal," it may include cases where there is an error due to manufacturing variations, etc. The error is, for example, within 10%.

[0019] 1 is a diagram illustrating an example of a control circuit 100 according to an embodiment of the present invention. The control circuit 100 controls a power semiconductor 200. The power semiconductor 200 receives a control signal V applied to a control terminal 204. g The power semiconductor 200 of this example has a main element 202 and a sense element 206. The power semiconductor 200 may be formed on a silicon substrate, or may be formed on a compound semiconductor substrate such as SiC.

[0020] The main element 202 in this example is a transistor such as an IGBT or a MOSFET. The main element 202 is driven by a control signal V applied to a control terminal 204. g The main current I according to D The main current I D is, for example, the drain current in a MOSFET or the collector current in an IGBT. D Sense current I according to S The sense element 206 may be formed in the same chip as the main element 202, or may be formed in a different chip.

[0021] The sense element 206 in this example is an IGBT or MOSFET provided in parallel with the main element 202. The gate terminal of the sense element 206 receives the same control signal V as the gate terminal of the main element 202. g In this example, the main current I D and the sense current I S That is, the ratio of the main current I D The sense current I is proportional to S As an example, the sense current I S is the main current I D The channel area is 1 / 1000 or less and 1 / 100,000 or more of the area of ​​the channel. The channel area is the area of ​​the region where the channel is formed in a cross section perpendicular to the direction of current flow. The so-called channel width may also be used as the channel area.

[0022] The control circuit 100 detects the sense current I S By detecting this, it is possible to detect whether an overcurrent is flowing through the main element 202. For example, if the main element 202 is an element of the upper arm or lower arm of an inverter circuit, a large short-circuit current will flow through the main element 202 if the elements of the upper arm and lower arm are simultaneously turned on. A short-circuit current is an example of an overcurrent. This specification describes the operation of the control circuit 100 when a short-circuit current flows through the main element 202, but the control circuit 100 may also operate in the same way when other types of overcurrent flow through the main element 202.

[0023] When the control circuit 100 determines that a short-circuit current is flowing through the main element 202, the control circuit 100 D For example, when the control circuit 100 detects a short-circuit current, it forcibly turns off the main element 202. By this control, the main element 202 can be protected from the short-circuit current.

[0024] The magnitude of the short-circuit current flowing through the main element 202 or the short-circuit energy applied to the main element 202 is determined by the control signal V applied to the main element 202. g As an example, the control signal V g The higher the voltage value, the larger the short-circuit current or short-circuit energy applied to the main element 202. The larger the short-circuit current or short-circuit energy applied to the main element 202, the more likely it is that the short-circuit withstand capability of the main element 202 will be exceeded, and the more likely it is that the main element 202 will be destroyed. In particular, when the main element 202 is made of SiC, the short-circuit withstand capability tends to be small, and the short-circuit energy applied to the main element 202 will be more likely to exceed the short-circuit withstand capability.

[0025] The control circuit 100 of this example receives the control signal V g The control power supply voltage V that determines the amplitude of CC In response to this, the main current I flows through the main element 202. D This allows the main element 202 to be protected more appropriately. For example, the control circuit 100 may CC The higher the value, the earlier the main current I D This prevents the main element 202 from being damaged. CC is the control signal V g The control signal V may be a voltage that defines the maximum value of g The minimum value of the control power supply voltage V may be determined by a reference potential (for example, 0 V). CC The main current I according to D The control of this will be described later.

[0026] The control circuit 100 of this example is supplied with a control power supply voltage V CC and the input signal VIN The input signal V IN is a signal input from the outside to control the operation of the power semiconductor 200. In this example, the input signal V IN is a signal that indicates a first logic value (for example, logic L) during a period when the power semiconductor 200 should be in an ON state, and indicates a second logic value (for example, logic H) during a period when the power semiconductor 200 should be in an OFF state. IN and the control power supply voltage V CC A control signal V having an amplitude according to g Generate.

[0027] The control circuit 100 includes a detection value comparison unit 102, a protection unit 120, and a protection control unit 130. The control circuit 100 of this example further includes a detection resistor 101, a current threshold generation unit 107, a filter 110, a set / reset latch 150, a logical OR circuit 152, and a charge / discharge control unit 140.

[0028] The charge / discharge control unit 140 controls the control power supply voltage V CC , the reference potential, and the input signal V IN Based on this, the control signal V g The charge / discharge control unit 140 of this example has a charging element 142, a discharging element 144, a charging resistor 146, and a discharging resistor 148. The charging element 142 and the discharging element 144 generate an input signal V IN In this example, the charging element 142 is a P-channel MOSFET, and the discharging element 144 is an N-channel MOSFET. The charging element 142 is a transistor that performs a switching operation in response to a control power supply voltage V CC is applied to the control terminal 204 or the discharge element 144. The discharge element 144 is provided between the charging element 142 and the reference potential. The discharge element 144 in this example is provided between the discharge resistor 148 and the reference potential. The charging resistor 146 is provided between the charging element 142 and the discharge element 144. The discharge resistor 148 is provided between the charging resistor 146 and the discharge element 144. The connection point of the charging resistor 146 and the discharge resistor 148 is connected to the control terminal 204 of the power semiconductor 200.

[0029] In this example, the input signal V IN becomes L logic, the charging element 142 is turned on and the discharging element 144 is turned off. As a result, the control terminal 204 is supplied with the control power supply voltage V CC is applied, and the capacitance of the control terminal 204 is charged. g The voltage value of the control signal V g becomes higher than the threshold voltage of the main element 202, the main element 202 transitions to the ON state. The threshold voltage of the sense element 206 is the same as the threshold voltage of the main element 202. Therefore, the sense element 206 switches in synchronization with the main element 202.

[0030] Input signal V IN When the control voltage V becomes logic H, the charging element 142 is turned off and the discharging element 144 is turned on. As a result, the control terminal 204 is connected to the reference potential via the discharging resistor 148, and the capacitance of the control terminal 204 is discharged. Therefore, the control voltage V g The voltage value of the control signal V g becomes lower than the threshold voltage of the main element 202, the main element 202 transitions to the OFF state. IN The switching of the power semiconductor 200 is controlled in accordance with the

[0031] The detection resistor 101 is provided between the sense element 206 and a reference potential. The detection resistor 101 receives the sense current I S As a result, the sense current I S and resistance value R S The sense voltage V according to the product of S Generate.

[0032] The detection value comparison unit 102 detects the main current I D The current detection value (in this example, the sense voltage V S voltage value) and the set current threshold V SC The detection value comparison unit 102 receives a sense voltage VS is input, and the current threshold V SC The detection value comparison unit 102 is an operational amplifier to which the sense voltage V S is the current threshold V SC The current comparison result S1 in this example is a signal that indicates H logic when the current detection value exceeds the current threshold, and indicates L logic when the current detection value is equal to or less than the current threshold.

[0033] The filter 110 detects the sense voltage V S is the current threshold V SC , and outputs a period determination signal SC indicating whether or not the state in which the current comparison result S1 indicates H logic has continued for a period longer than the set duration. In this example, the period determination signal SC indicates H logic when the state in which the current comparison result S1 indicates H logic has continued for a period longer than the specified duration, and indicates L logic in other cases. The filter 110 is, for example, a low-pass filter that removes specified high-frequency components. The length of the duration can be adjusted by controlling the cutoff frequency of the filter 110. In other examples, the control circuit 100 does not include the filter 110, and the duration may not be set. In other words, the duration may be 0. In this case, the current comparison result S1 is input to the input terminal S of the set-reset latch 150, and when the current detection value exceeds the current threshold, the main current I D The current suppression starts.

[0034] When the period determination signal SC indicates a logic H, the protection unit 120 reduces the main current I D The protection unit 120 of this example suppresses the input signal V while the period determination signal SC indicates the H logic. IN , the control terminal 204 of the power semiconductor 200 is connected to the reference potential. g The voltage value of decreases, and the main current I D is suppressed.

[0035] The protection unit 120 of this example includes a first protection element 121. The first protection element 121 detects a sense voltage VS is the current threshold V SC If the state where the voltage exceeds the set value continues for a period longer than the set duration, the main current I D The first protection element 121 in this example is a MOSFET to whose gate terminal a signal corresponding to the period determination signal SC is input. The first protection element 121 switches whether or not the control terminal 204 of the power semiconductor 200 is connected to the reference potential, depending on the signal input to the gate terminal. When the first protection element 121 is turned on, the charge in the capacitance of the control terminal 204 is extracted, and the power semiconductor 200 is turned off. As a result, the main current I D is suppressed.

[0036] The gate terminal of the first protection element 121 in this example is connected to the protection signal S output by the set-reset latch 150. SC The first protection element 121 of this example receives the protection signal S SC is in the ON state when it is H logic, and in the OFF state when it is L logic.

[0037] The set / reset latch 150 holds and outputs the logical value of the current comparison result S1 in the detection value comparison unit 102 (in this example, the logical value of the period determination signal SC), and outputs the control signal V IN indicates a logical value that should turn off the power semiconductor 200. In the set-reset latch 150 of this example, the period determination signal SC is input to the set terminal S, and the input signal V is input to the reset terminal R. IN is input, and the protection signal S is output from the output terminal Q. SC The set-reset latch 150 of this example outputs the input signal V IN The protection signal S at logic H is SC Outputs the input signal V IN When the period determination signal SC is maintained at logic H after the transition from logic L to logic H, the set-reset latch 150 outputs the protection signal S at logic H. SC The input signal V INWhen the period determination signal SC indicates a logic L at the timing when the protection signal S SC may be output.

[0038] The OR circuit 152 receives the protection signal S SC and the control signal V IN The charge / discharge control unit 140 controls whether or not to charge the capacitance of the control terminal 204 of the power semiconductor 200, depending on the output of the OR circuit 152. The OR circuit 152 in this example outputs a logical sum of the input signal V IN and protection signal S SC When both of the input signals V IN and protection signal S SC When at least one of them indicates H logic, the charging element 142 may be controlled to be in an ON state.

[0039] With this configuration, the control circuit 100 controls the input signal V IN However, as described above, the control circuit 100 protects the power semiconductor 200 from an overcurrent by switching the power semiconductor 200 in response to the control signal V g The control power supply voltage V that determines the amplitude of CC In response to this, the main current I flows through the main element 202. D Suppress.

[0040] The protection control unit 130 controls the control power supply voltage V CC Based on this, the current threshold V SC , the predetermined duration defined by the filter 110, and / or the rate at which charges are extracted from the control terminal 204. The protection control unit 130 in the example of FIG. CC Based on the current threshold V SC Control.

[0041] The protection control unit 130 is CC detection circuit 132. CC The detection circuit 132 detects the control power supply voltage VCC Voltage comparison result SV according to the level CC Outputs the voltage comparison result SV CC is the control power supply voltage V CC may be a binary signal indicating whether or not the control power supply voltage V exceeds a predetermined voltage threshold. CC The protection control unit 130 may use three or more values ​​to indicate the voltage comparison result SV CC The current threshold V generated by the current threshold generating unit 107 is SC Control.

[0042] The current threshold value generating unit 107 generates a voltage comparison result SV CC The current threshold generating unit 107 of this example includes a selecting unit 103, a threshold power supply 108, and a threshold power supply 109. The threshold power supply 108 selects and outputs a current threshold V SC-H The threshold power supply 109 generates a current threshold V SC-H Lower current threshold V SC-L Generates a current threshold V SC-L is the current threshold V SC-H It may be 75% or less, 50% or less, or 25% or less.

[0043] The selection unit 103 selects the voltage comparison result SV CC The selection unit 103 in this example selects and outputs a current threshold value according to the control power supply voltage V CC exceeds the voltage threshold, the current threshold V SCーL Select the control power supply voltage V CC is less than the voltage threshold, the current threshold V SC―H That is, the current threshold generator 107 selects the control power supply voltage V CC The higher the current threshold V SC can be lowered.

[0044] Current threshold V SC By lowering the sense voltage V S When the sense voltage V is lower, the current comparison result S1 becomes logic H and current suppression begins. S When the time waveform of changes with a predetermined slope, the current threshold VSC By lowering S Detects an increase in the main current I D Therefore, the control power supply voltage V CC The timing for starting the current suppression can be adjusted depending on the current, and the power semiconductor 200 can be protected more appropriately.

[0045] Figure 2 shows the V CC FIG. 1 is a diagram illustrating an example of a detection circuit 132. CC The detection circuit 132 detects the control power supply voltage V CC is a predetermined voltage threshold V th1 In this example, V CC The detection circuit 132 includes an operational amplifier 134 and a threshold power supply 136 .

[0046] The threshold power supply 136 provides a voltage threshold V th1 The operational amplifier 134 receives the control power supply voltage V CC is input, and the negative input terminal is connected to the voltage threshold V th1 The operational amplifier 134 receives the control power supply voltage V CC is the voltage threshold V th1 When the control power supply voltage V CC is the voltage threshold V th1 The current comparison result S1, which becomes logic L, is output in the following cases:

[0047] 3 is a diagram showing an example of the filter 110. The filter 110 of this example includes an inverter 111, transistors 112 to 115, a current source 116, a capacitor 117, an operational amplifier 119, and a threshold power supply 118.

[0048] The inverter 111 inverts the logical value of the current comparison result S1 and outputs it. The transistor 112 is provided between a power supply voltage VC and a reference potential. In this example, the transistor 112 is a P-channel MOSFET having a source terminal to which the power supply voltage VC is applied and a drain terminal and a gate terminal connected together. The current source 116 is provided between the drain terminal of the transistor 112 and the reference potential and determines the current flowing through the transistor 112.

[0049] The transistor 113 is a P-channel MOSFET provided in parallel with the transistor 112. A power supply voltage VC is applied to the source terminal of the transistor 113, and the gate terminal is connected to the drain terminal of the transistor 112. A current equivalent to that flowing through the transistor 113 flows as in the transistor 112.

[0050] The transistor 114 is a P-channel MOSFET having a source terminal connected to the drain terminal of the transistor 113 and a gate terminal connected to the output terminal of the inverter 111. The transistor 114 is controlled to an ON state when the current comparison result S1 is at a logical H.

[0051] The transistor 115 is an N-channel MOSFET having a drain terminal connected to the drain terminal of the transistor 113, a source terminal to which a reference potential is applied, and a gate terminal connected to the output terminal of the inverter 111. The transistor 114 is controlled to an ON state when the current comparison result S1 is at a logical L.

[0052] In this example, transistors 114 and 115 are controlled so that when one is on, the other is off. A capacitor 117 is connected to the drain terminals of transistors 114 and 115. When transistor 114 is on, capacitor 117 is charged with a current of a magnitude determined by current source 116, and the voltage of the capacitor gradually increases. When transistor 115 is on, capacitor 117 is discharged, and the voltage of the capacitor gradually decreases.

[0053] The operational amplifier 119 has a capacitor 117 connected to its positive input terminal and a voltage threshold V th2 The operational amplifier 119 detects whether the voltage across the capacitor 117 exceeds the voltage threshold V th2 When the voltage of the capacitor 117 exceeds the voltage threshold V th2 A period determination signal SC that becomes logic L is output in the following cases.

[0054] As described above, when the current comparison result S1 is logic H (that is, when an overcurrent is detected), the capacitor 117 is charged and the voltage of the capacitor 117 gradually increases. th2 , the period determination signal SC becomes the H logical value. The slope of the voltage waveform of the capacitor 117 is determined according to the capacitance C1 of the capacitor 117. Therefore, after the charging of the capacitor 117 starts, when the voltage of the capacitor 117 reaches the voltage threshold V th2 The period until the current comparison result S1 exceeds the threshold voltage Vcc is determined by the capacitance C1. Therefore, if the current comparison result S1 indicates a logical H value during a period according to the capacitance C1, the period determination signal SC becomes a logical H value. The period according to the capacitance C1 corresponds to the duration described above.

[0055] 4 is a diagram showing an example of the configuration of the selection unit 103. The selection unit 103 of this example includes an inverter 104, a transistor 105, and a transistor 106. The inverter 104 outputs the voltage comparison result SV CC The logical value of is inverted and output.

[0056] The transistor 105 switches whether or not to connect the threshold power supply 108 to the negative input terminal of the detection value comparing unit 102. In this example, the transistor 105 is an N-channel MOSFET whose drain terminal is connected to the negative input terminal of the detection value comparing unit 102, whose source terminal is connected to the threshold power supply 108, and whose gate terminal receives the output of the inverter 104.

[0057] The transistor 106 switches whether or not to connect the threshold power supply 109 to the negative input terminal of the detection value comparison unit 102. In this example, the transistor 106 has a drain terminal connected to the negative input terminal of the detection value comparison unit 102, a source terminal connected to the threshold power supply 109, and a gate terminal connected to the voltage comparison result SV CC This is an N-channel MOSFET to which the control power supply voltage V CC is the voltage threshold V th1 When the current threshold V SC-L Select the control power supply voltage V CC is the voltage threshold Vth1 When the current threshold V SC-H You can select.

[0058] Fig. 5 is a diagram showing another example of the configuration of the control circuit 100. The control circuit 100 of this example further includes an AND circuit 154 and a second protection element 122 in addition to the configuration of the control circuit 100 described with reference to Figs. 1 to 4. The other configuration is the same as any of the aspects described with reference to Figs. 1 to 4.

[0059] The second protection element 122 is provided in parallel with the first protection element 121 in the protection unit 120. In this example, the second protection element 122 is an N-channel MOSFET having a drain terminal connected to the control terminal 204 and a source terminal connected to a reference potential. The AND circuit 154 outputs a protection signal S SC and the output signal S VCC The logical product of these is input to the gate terminal of the second protection element 122.

[0060] In the protection unit 120 of this example, a first protection element 121 and a second protection element 122 are provided in parallel. The first protection element 121 and the second protection element 122 are examples of extraction transistors that control whether or not the control terminal 204 is connected to the reference potential. The first protection element 121 and the second protection element 122 may be collectively treated as one extraction transistor. The main current I D When suppressing this, the channel area of ​​the extraction transistor is controlled by controlling the states of the first protection element 121 and the second protection element 122, and the speed at which charges are extracted from the capacitance of the control terminal 204 can be adjusted.

[0061] The first protection element 121 of this example is a protection signal S output by the set-reset latch 150. SC It operates according to the protection signal S SC indicates H logic, the first protection element 121 is always in the ON state, and the main current I D is suppressed.

[0062] The second protection element 122 of this example is connected to the protection signal S output by the set-reset latch 150. SCand the voltage comparison result SV CC It operates based on the logical AND of the protection signal S SC indicates H logic, and the voltage comparison result S VCC indicates H logic, the second protection element 122 is additionally turned on, the timing at which the power semiconductor 200 is cut off is earlier, and the main current I D As described above, the protection signal S SC indicates a logic high when the sense voltage V S is the current threshold V SC The voltage comparison result S VCC indicates a logic high when the control power supply voltage V CC is the set voltage threshold V th1 This indicates a state in which the value exceeds the limit.

[0063] The protection control unit 130 of this example uses the voltage comparison result S VCC is input to the AND circuit 154. As a result, the protection control unit 130 outputs the control power supply voltage V CC When an overcurrent is detected, the protection control unit 130 of this example controls the speed at which the charge is extracted from the capacitance of the control terminal 204 based on the control power supply voltage V CC is the voltage threshold V th1 If the voltage comparison result S exceeds , the second protection element 122 is additionally turned on to increase the speed at which the charges are extracted. The magnitude of the current flowing through the second protection element 122 may be the same as or different from the magnitude of the current flowing through the first protection element 121. VCC If the voltage comparison result S VCC The charge may be drawn from the control terminal 204 with a current amount according to the value of

[0064] According to this example, the control power supply voltage V CC When the main current I D On the other hand, the control power supply voltage V CCWhen the voltage is not high, the generation of a surge can be suppressed by slowing down the speed at which the charge is extracted from the control terminal 204.

[0065] In the example of FIG. 5, the protection control unit 130 calculates the charge extraction rate in the protection unit 120 and the current threshold V generated by the current threshold generation unit 107. SC In another example, the protection control unit 130 controls the rate at which the charge is extracted in the protection unit 120, and the current threshold V SC does not need to be controlled.

[0066] 5, the protection control unit 130 controls the channel area of ​​the extraction transistor in the protection unit 120. In another example, the protection control unit 130 may control the level of the gate voltage applied to the extraction transistor. The protection control unit 130 controls the control power supply voltage V CC The higher the control power supply voltage V CC The higher the charge extraction rate, the faster the charge extraction rate.

[0067] The protection control unit 130 may control at least one of the channel area and the gate voltage. SC The gate voltage may be controlled by adjusting the amplitude of the protection signal S SC The amplitude of the signal can be adjusted.

[0068] 6 is a diagram showing another example of the operation of the protection control unit 130. The protection unit 120 of this example further includes a variable resistor 128. The variable resistor 128 is an example of a discharge resistor provided in a discharge path that discharges the control terminal 204. The variable resistor 128 is provided in series with the first protection element 121. The protection control unit 130 may control the resistance value of the variable resistor 128 to control the current flowing through the first protection element 121 and to control the rate at which charges are extracted from the capacitance of the control terminal 204. The protection control unit 130 controls the control power supply voltage V CC The higher the control power supply voltage V, the smaller the resistance value of the variable resistor 128 can be set.CC The higher the charge extraction rate, the faster the charge extraction rate.

[0069] The variable resistor 128 may also be provided for the second protection element 122. The protection control unit 130 may control the rate at which the charges are extracted by controlling at least one of the resistance value of the variable resistor 128, the channel area of ​​the extraction transistor, and the gate voltage of the extraction transistor.

[0070] The protection control unit 130 compares the voltage comparison result SV CC The resistance value of the discharge resistor 148 (see FIG. 1 or FIG. 5) may be controlled based on the control power supply voltage V. The discharge resistor 148 is an example of a discharge resistor provided in a discharge path that discharges the control terminal 204. The protection control unit 130 controls the control power supply voltage V CC The higher the resistance value of the discharge resistor 148, the smaller the resistance value of the discharge resistor 148. This allows the discharge rate of the control terminal 204 by the discharge element 144 to be controlled.

[0071] 7 is a diagram showing another example of the operation of the protection control unit 130. The protection control unit 130 of this example performs the voltage comparison result SV CC The protection control unit 130 controls the duration set in the filter 110 based on the control power supply voltage V CC The higher the control power supply voltage V CC The higher the value, the earlier the main current I D can be suppressed.

[0072] For example, if the capacitor 117 of the filter 110 has a variable capacitance, the protection control unit 130 controls the control power supply voltage V CC The capacitance of the capacitor 117 can be made smaller as the control power supply voltage V CC 3 is a variable current source, the protection control unit 130 controls the control power supply voltage V CC The higher the control power supply voltage V CC3 is a variable power supply, the protection control unit 130 controls the control power supply voltage V CC The higher the threshold voltage V th2 This allows the control power supply voltage V CC The higher the value, the shorter the duration can be set.

[0073] The protection control unit 130 controls the duration set in the filter 110 and the current threshold V SC and the control of the rate at which charges are extracted from the control terminal 204. CC Current threshold V according to SC and the control power supply voltage V CC When combining the control of the charge extraction rate according to the current threshold V SC After changing the extraction rate, the extraction transistors (for example, the first protection element 121 and the second protection element 122) whose extraction rate has been changed may be controlled to be in the ON state.

[0074] In this case, the withdrawal speed setting is changed by the current threshold V SC For example, after changing the setting of the withdrawal speed, the protection control unit 130 may change the current threshold V to be input to the detection value comparison unit 102. SC The extraction speed setting may be changed by changing the current threshold V SC This may be done simultaneously with or after the change of the current threshold V SC Before changing the pull-out speed, if the pull-out transistor whose pull-out speed has been changed is controlled to the on state, the control signal V g The duration control set in the filter 110 is performed by adjusting the current threshold V SC This may be done before, at the same time as, or after the change.

[0075] The sense voltage V S By adjusting the gain of DHowever, the timing at which the suppression of the sense voltage V S is the main current I D It may also be used for purposes other than overcurrent detection, such as calculating the current value of the sense voltage V S Changing the gain of the detection resistor 101 will affect these applications. D The timing of suppression can be adjusted.

[0076] FIG. 8 shows the short-circuit current I applied to the power semiconductor 200. SC and short circuit energy E SC The horizontal axis of FIG. 8 represents the control power supply voltage V CC The vertical axis indicates the short-circuit current I SC and short circuit energy E SC This shows:

[0077] The solid line in Figure 8 indicates the current threshold V SC In this case, the constant current threshold V SC-H The control power supply voltage V CC With the increase of SC and short circuit energy E SC Both of these are increasing.

[0078] The dotted line in Figure 8 indicates the control power supply voltage V CC Depending on the current threshold V SC Specifically, the control power supply voltage V CC When V exceeds 17.5V, the current threshold V SC-L Select the control power supply voltage V CC If V is less than 17.5V, the current threshold V SC-H As shown in Figure 8, the current threshold V SC-L By selecting SC and short circuit energy E SC 8, both of the current threshold V SCIn the example shown here, the short-circuit current I is controlled, but in the example where the charge extraction speed and the duration are controlled, the short-circuit current I SC and short circuit energy E SC can be reduced.

[0079] 9 is a diagram showing an example of a power supply circuit 300 according to an embodiment of the present invention. The power supply circuit 300 supplies power to a load 330 in accordance with power supplied from an external power supply 310. The AC power output from the external power supply 310 is rectified by a rectifier 320 and a capacitor 240 and input to the power supply circuit 300 of this example. The load 330 is, for example, a three-phase motor, but is not limited to this.

[0080] The power supply circuit 300 includes a semiconductor module 210, a control circuit 100, an isolation circuit 220, and a microcontroller 230. The semiconductor module 210 supplies power to a load 330 based on power supplied from a rectifier device 320. The semiconductor module 210 includes at least one power semiconductor 200 described with reference to FIGS. 1 to 8. Power is supplied to the load 330 by operating the power semiconductor 200.

[0081] The semiconductor module 210 of this example is a three-phase inverter. The semiconductor module 210 includes an upper arm power semiconductor 200 and a lower arm power semiconductor 200 in the inverter for each phase. In the example of Fig. 9, the power semiconductors 200-U and 200-X correspond to the upper arm and lower arm of one phase. The same applies to the power semiconductors 200-V and 200-Y, and the power semiconductors 200-W and 200-Z.

[0082] 9, each power semiconductor 200 has a MOSFET and a built-in diode. In another example, each power semiconductor 200 may have a switching element such as an IGBT or a BJT instead of a MOSFET. Furthermore, the power semiconductor 200 does not need to have a built-in diode, and may have an external diode such as a SiC-SBD instead of the built-in diode.

[0083] The control circuit 100 has the same function and configuration as any of the aspects described in Figures 1 to 8. The control circuit 100 controls each power semiconductor 200. The control circuit 100 described in Figures 1 to 8 may be provided for each power semiconductor 200.

[0084] The semiconductor module 210 has a module case that houses the power semiconductor 200. The module case may be made of resin or the like. The control circuit 100 may be provided inside the module case. Alternatively, the control circuit 100 may be provided outside the module case.

[0085] The isolation circuit 220 transmits signals while maintaining electrical isolation between the control circuit 100 and the microcontroller 230. The isolation circuit 220 may include, for example, a photocoupler. This allows signals to be transmitted between the control circuit 100 and the microcontroller 230 even when the control circuit 100 and the microcontroller 230 operate on different power supply voltages.

[0086] The microcontroller 230 transmits a signal to the control circuit 100 based on a command signal input from the outside. For example, the microcontroller 230 transmits a control signal V IN and transmits it to the control circuit 100. The microcontroller 230 may also receive a signal from the control circuit 100. For example, the microcontroller 230 may receive a signal indicating the state of the control circuit 100, such as whether the control circuit 100 has detected an overcurrent. The microcontroller 230 may notify the signal to an external device, and may generate a control signal V based on the signal. IN may be generated.

[0087] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention. [Explanation of symbols]

[0088] 100 control circuit, 101 detection resistor, 102 detection value comparison unit, 103 selection unit, 104 inverter, 105 transistor, 106 transistor, 107 current threshold generation unit, 108 threshold power supply, 109 threshold power supply, 110 filter, 111 inverter, 112, 113, 114, 115 transistor, 116 current source, 117 capacitor, 118 threshold power supply, 119 operational amplifier, 120 protection unit, 121 first protection element, 122 second protection element, 128 variable resistor, 130 protection control unit, 132 V CC Detection circuit, 134 operational amplifier, 136 threshold power supply, 140 charge / discharge control section, 142 charging element, 144 discharging element, 146 charging resistor, 148 discharging resistor, 150 set / reset latch, 152 logical OR circuit, 154 logical AND circuit, 200 power semiconductor, 202 main element, 204 control terminal, 206 sense element, 210 semiconductor module, 220 isolation circuit, 230 microcontroller, 240 capacitor, 300 power supply circuit, 310 external power supply, 320 rectifier, 330 load

Claims

1. A control circuit for a power semiconductor that operates in response to a control signal applied to a control terminal, a detection value comparison unit that compares a current detection value corresponding to a main current flowing through the power semiconductor with a set current threshold; a protection unit that suppresses the main current flowing through the power semiconductor when a state in which the current detection value exceeds the current threshold continues for a period longer than a set duration; a protection control unit that controls at least one of the current threshold, the duration, and a rate at which charges are extracted from the control terminal based on a control power supply voltage that defines the amplitude of the control signal; A control circuit comprising:

2. The protection control unit controls the current threshold. The control circuit of claim 1 .

3. The protective part is a first protection element that suppresses the main current flowing through the power semiconductor when a state in which the current detection value exceeds the current threshold continues for a period longer than a set duration; a second protection element that further suppresses the main current flowing through the power semiconductor when the state in which the current detection value exceeds the current threshold continues for a period longer than a set duration and the control power supply voltage exceeds a set voltage threshold; 3. The control circuit of claim 2, comprising:

4. a set / reset latch that holds and outputs a current comparison result from the detection value comparison unit and sets an output to an initial value when the control signal indicates a logical value that should turn off the power semiconductor; the protection control unit outputs a voltage comparison result between the control power supply voltage and a voltage threshold; the first protection element operates in response to an output of the set-reset latch; The second protection element operates based on a logical product of the output of the set-reset latch and the voltage comparison result.

4. The control circuit of claim 3.

5. a logical OR circuit that outputs a logical OR of the output of the set / reset latch and the control signal; a charge / discharge control unit that controls whether or not to charge the control terminal of the power semiconductor according to an output of the OR circuit; The control circuit of claim 4 further comprising:

6. The protection control unit controls the duration. The control circuit of claim 1 .

7. The protection control unit controls the extraction speed. The control circuit of claim 1 .

8. a pull-out transistor that controls whether or not the control terminal is connected to a reference potential; The protection control unit controls at least one of a channel area of ​​the extraction transistor and a gate voltage applied to the extraction transistor.

8. The control circuit of claim 7.

9. a discharge resistor provided in a path for discharging the control terminal; The protection control unit controls the resistance value of the discharge resistor.

8. The control circuit of claim 7.

10. The protection control unit further controls the current threshold value, The protection control unit controls the extraction transistor, the extraction speed of which has been changed, to an on state after changing the current threshold.

9. The control circuit of claim 8.

11. a control circuit according to claim 1; The power semiconductor A power supply circuit comprising:

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