Electronic circuits, power converters, and inverters

Abstract

To provide electronic circuitry that can shorten a switching delay while preventing a noise generation.SOLUTION: Electronic circuitry includes: a current output circuit configured to output a drive current to a switching element; a first detection circuit configured to detect a timing at which a voltage between output terminals of the switching element starts to change; and a control circuit configured to cause the current output circuit to start outputting a first drive current in accordance with a command signal that instructs switching operation of the switching element. The control circuit switches the drive current output from the current output circuit to a second drive current smaller than the first drive current on the basis of the timing at which the voltage between the output terminals starts to change, the timing being detected by the first detection circuit.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] This embodiment relates to an electronic circuit, a power conversion device, and an inverter.

Background Art

[0002] In the field of power electronics, semiconductor switching devices such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors) are used.

[0003] When a switching device is turned on, there is a delay (switching delay) between when the gate voltage starts to rise and when the drain current starts to flow. In order to shorten the switching delay, the drive current supplied until the voltage between the drain and source starts to change is increased. However, if the drive current remains large even after the voltage between the drain and source starts to change, it causes noise due to the rapid time change of the voltage between the drain and source.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] This embodiment aims to solve the above-mentioned problems and to provide an electronic circuit that can shorten switching delay while suppressing noise generation. [Means for solving the problem]

[0006] To solve the above problems, the electronic circuit according to this embodiment includes a current output circuit that outputs a drive current to a switching element, a first detection circuit that detects the start timing of a voltage change between the output terminals of the switching element, and a control circuit that causes the current output circuit to start outputting a first drive current in response to a command signal that instructs the switching operation of the switching element. The control circuit switches the drive current output from the current output circuit to a second drive current that is smaller than the first drive current, based on the start timing of the voltage change between the output terminals detected by the first detection circuit.

[0007] Furthermore, the power conversion device according to this embodiment is a power conversion device that includes two switching elements constituting an arm pair and two electronic circuits that supply drive current to each of the two switching elements, each of which includes a current output circuit that outputs drive current to the switching element, a first detection circuit that detects the start timing of a voltage change between the output terminals of the switching element, and a control circuit that causes the current output circuit to start outputting a first drive current in response to a command signal that instructs the switching operation of the switching element, and the control circuit switches the drive current output from the current output circuit to a second drive current that is smaller than the first drive current based on the start timing of the voltage change between the output terminals detected by the first detection circuit.

[0008] Furthermore, the inverter according to this embodiment includes a motor, two switching elements constituting an arm pair connected to the motor, and a power conversion circuit having three sets of two electronic circuits, each supplying a drive current to the two switching elements. Each electronic circuit includes a current output circuit that outputs a drive current to the switching elements, a first detection circuit that detects the start timing of a voltage change between the output terminals of the switching elements, and a control circuit that causes the current output circuit to start outputting a first drive current in response to a command signal that instructs the switching operation of the switching elements. The control circuit switches the drive current output from the current output circuit to a second drive current that is smaller than the first drive current, based on the start timing of the voltage change between the output terminals detected by the first detection circuit. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram showing the configuration of the motor control system according to Embodiment 1. [Figure 2] A diagram showing the internal configuration of the electronic circuit in Embodiment 1. [Figure 3] A timing chart illustrating the operation of the switching element driven by the drive current output from the current output circuit according to Embodiment 1. [Figure 4] This diagram shows an example of current flowing in from the load side when both switching elements constituting an arm pair are in the OFF state. [Figure 5] A diagram showing the internal configuration of the electronic circuit in Embodiment 2. [Figure 6] A timing chart illustrating the operation of the switching element driven by the drive current output from the current output circuit according to Embodiment 2. [Figure 7] A diagram showing the internal configuration of the electronic circuit in Embodiment 3. [Modes for carrying out the invention]

[0010] This embodiment will be described below with reference to the drawings. In the drawings, the same or corresponding elements are denoted by the same reference numerals, and detailed descriptions are omitted as appropriate.

[0011] (Embodiment 1) Figure 1 shows the configuration of a motor control system 1 according to Embodiment 1. The motor control system 1 includes a three-phase AC motor 2 as a load, a DC power supply 3, switching elements 11a to 11f constituting a three-phase inverter circuit 10, and electronic circuits 100a to 100f that drive the switching elements 11a to 11f, respectively. The motor control system 1 also includes a detection circuit 4 that detects the operating state of the switching elements 11a to 11f, and a signal supply circuit 5 that supplies PWM signals to the electronic circuits 100a to 100f. In this embodiment, a motor is used as an example load, but any electronic or electrical device driven by an AC power supply may be used as the load.

[0012] Switching elements 11a and 11b are N-channel MOSFETs. Switching elements 11a and 11b constitute the U-phase arm pair of the inverter circuit 10. Electronic circuit 100a controls the switching operation of switching element 11a, i.e., turn-on and turn-off, by controlling the drive current of switching element 11a, i.e., the gate current Ig. Electronic circuit 100b controls the switching operation of switching element 11b by controlling the drive current of switching element 11b.

[0013] Similarly, switching elements 11c and 11d are N-channel MOSFETs. Switching elements 11c and 11d constitute the V-phase arm pair of the inverter circuit 10. Electronic circuit 100c controls the switching operation of switching element 11c by controlling the drive current of switching element 11c. Electronic circuit 100d controls the switching operation of switching element 11d by controlling the drive current of switching element 11d.

[0014] Similarly, switching elements 11e and 11f are N-channel MOSFETs. Switching elements 11e and 11f constitute the W-phase arm pair of the inverter circuit 10. Electronic circuit 100e controls the switching operation of switching element 11e by controlling the drive current Ig of switching element 11e. Electronic circuit 100f controls the switching operation of switching element 11f by controlling the drive current of switching element 11f.

[0015] The detection circuit 4 detects the operating state of the switching elements 11a to 11f based on the current values ​​of the U, V, and W phases of the motor 2 and transmits this information to the signal supply circuit 5. Alternatively, the detection circuit 4 may detect the operating state of the switching elements 11a to 11f based on temperature information obtained by a temperature sensor (not shown) built into the motor 2. Or, the detection circuit 4 may detect the operating state of the switching elements 11a to 11f based on signals received from a control microcomputer (not shown).

[0016] The signal supply circuit 5 supplies PWM signals to the electronic circuits 100a to 100f as command signals instructing the switching operation of the switching elements 11a to 11f, based on the operating status of the switching elements 11a to 11f received from the detection circuit 4. The signal supply circuit 5 and the electronic circuits 100a to 100f operate according to a system clock (not shown).

[0017] Figure 2 shows the internal configuration of electronic circuits 100a to 100f. Since the configuration of electronic circuits 100a to 100f is identical, they will be referred to as electronic circuit 100 from now on. Similarly, the switching elements 11a to 11f will be referred to as switching element 11 from now on.

[0018] The electronic circuit 100 is a circuit that supplies a driving current to the switching element 11, and includes a first detection circuit 110, a second detection circuit 120, a current output circuit 130, and a control circuit 140.

[0019] The first detection circuit 110 detects the start timing of the voltage change between the output terminals of the switching element 11, that is, the timing when the drain-source voltage Vds starts to change at the time of turn-on. Specifically, the first detection circuit 110 detects the start timing of the voltage change between the output terminals of the switching element 11 by detecting the timing when the drain-source voltage Vds of the switching element 11 becomes equal to a predetermined first threshold voltage Vth1. In the first embodiment, the first threshold voltage Vth1 is set to a voltage within the range of 90% to 80% of the drain-source voltage Vds when the switching element 11 is non-conductive, as an example.

[0020] The first detection circuit 110 includes a comparator 111, a constant voltage source 112 that outputs the first threshold voltage Vth1, and a detection signal output circuit 113. The positive terminal of the comparator 111 is connected to the drain terminal of the switching element 11. The negative terminal of the comparator 111 is connected to the source terminal of the switching element 11 via the constant voltage source 112. The detection signal output circuit 113 transmits a detection signal to the control circuit 140 when the output voltage of the comparator 111 becomes 0, that is, when the drain-source voltage Vds of the switching element 11 becomes equal to the first threshold voltage Vth1.

[0021] The second detection circuit 120 detects the completion timing of the voltage change between the output terminals of the switching element 11, that is, the timing when the drain-source voltage Vds decreases to below a predetermined value during turn-on. More specifically, the second detection circuit 120 detects the completion timing of the voltage change between the output terminals of the switching element 11 by detecting the timing when the drain-source voltage Vds of the switching element 11 becomes equal to a predetermined second threshold voltage Vth2. In this embodiment 1, the second threshold voltage Vth2 is set, for example, to a voltage within the range of 20% to 10% of the drain-source voltage Vds when the switching element 11 is not conducting.

[0022] The second detection circuit 120 includes a comparator 121, a constant voltage source 122 that outputs a second threshold voltage Vth2, and a detection signal output circuit 123. The positive terminal of the comparator 121 is connected to the drain terminal of the switching element 11. The negative terminal of the comparator 121 is connected to the source terminal of the switching element 11 via the constant voltage source 122. The detection signal output circuit 123 transmits a detection signal to the control circuit 140 when the output voltage of the comparator 121 becomes 0, that is, when the drain-source voltage Vds of the switching element 11 becomes equal to the second threshold voltage Vth2.

[0023] The current output circuit 130 outputs a drive current to the switching element 11. The control circuit 140, in response to the rising edge of the PWM signal supplied from the signal supply circuit 5, causes the current output circuit 130 to start outputting a first drive current Ig1, and then controls the magnitude of the drive current output from the current output circuit 130 based on the start timing of the voltage change between the output terminals of the switching element 11 detected by the first detection circuit 110 and the completion timing of the voltage change between the output terminals of the switching element 11 detected by the second detection circuit 120.

[0024] The control circuit 140 is implemented by at least one processor. The processor includes, for example, arithmetic circuits and is implemented by circuits that perform analog signal processing or circuits that perform digital signal processing. The processor may be a CPU (Central Processing Unit), a DSP (Digital Signal Processor), a general-purpose processor, a microprocessor, an ASIC, an FPGA, a semiconductor chip, a discrete component, or a combination thereof.

[0025] Figure 3 is a timing chart illustrating the operation of the switching element 11 driven by the drive current output from the current output circuit 130 and the drive current output from the current output circuit 130.

[0026] At time t1, when the rising edge of the PWM signal is detected, the control circuit 140 causes the current output circuit 130 to start outputting the first drive current Ig1 and starts precharging the switching element 11 (time t2). Here, the period from time t1 to time t2 corresponds to the delay time required from when the control circuit 140 detects the rising edge of the PWM signal until the current output circuit 130 actually outputs the first drive current Ig1.

[0027] The larger the first drive current Ig1, the shorter the time from when the gate voltage Vg of the switching element 11 starts to rise until the drain-source voltage Vds starts to change, i.e., the switching delay. Therefore, it is preferable to set the first drive current Ig1 to be as large as possible.

[0028] Furthermore, the longer the period for which the first drive current Ig1 is supplied, the shorter the switching delay can be. However, if the drive current remains large even after the drain-source voltage Vds begins to change, noise will be generated due to the rapid time change in the drain-source voltage Vds. For this reason, it is preferable to supply the first drive current Ig1 until just before the drain-source voltage Vds begins to change, that is, just before the start of the voltage change between the output terminals of the switching element 11.

[0029] At time t3, the first detection circuit 110 detects the start of a voltage change between the output terminals of the switching element 11, that is, that the drain-source voltage Vds of the switching element 11 has become equal to the first threshold voltage Vth1. The control circuit 140 switches the drive current output from the current output circuit 130 from the first drive current Ig1 to the second drive current Ig2, and starts charging the switching element 11.

[0030] The time required from the start to the completion of the voltage change between the output terminals of the switching element 11 depends on the magnitude of the second drive current Ig2. Specifically, the larger the second drive current Ig2, the shorter the time required from the start to the completion of the voltage change. However, if the second drive current Ig2 is made too large, it can cause noise due to the rapid time change of the drain-source voltage Vds. Therefore, it is preferable that the second drive current Ig2 be set to be smaller than the first drive current Ig1 and as large as possible within a range where noise is not generated.

[0031] At time t4, the second detection circuit 120 detects that the voltage change between the output terminals of the switching element 11 is complete, that is, that the drain-source voltage Vds of the switching element 11 has become equal to the second threshold voltage Vth2. The control circuit 140 switches the drive current output from the current output circuit 130 from the second drive current Ig2 to the third drive current Ig3 and starts post-charging of the switching element 11.

[0032] The length of the post-charge period depends on the magnitude of the third drive current Ig3. Specifically, the larger the third drive current Ig3, the shorter the post-charge period can be. Also, since the switching element 11 is already conducting during the post-charge period, there is no need to consider the generation of noise. For this reason, it is preferable that the magnitude of the third drive current Ig3 be set to be larger than the second drive current Ig2, and preferably set to be as large as possible, similar to the first drive current Ig. In this embodiment 1, as an example, the third drive current Ig3 is set to be equal in magnitude to the first drive current Ig1.

[0033] As described above, the control circuit 140 of the electronic circuit 100 according to this embodiment 1 starts outputting a first drive current Ig1 to the current output circuit 130 in accordance with the rising edge of the PWM signal. Then, when the first detection circuit 110 detects the start timing of the voltage change between the output terminals of the switching element 11, it switches the drive current output from the current output circuit 130 to a second drive current Ig2.

[0034] Due to the above features, the electronic circuit 100 according to this embodiment 1 can shorten the switching delay while suppressing noise generation when supplying drive current to the switching element. In non-referenced document 1, the pre-charge period is fixed, so in order to allow for margin considering variations in the characteristics of the switching element and the electronic circuit, the pre-charge period cannot be extended until just before the start of the voltage change between the output terminals of the switching element. In contrast, in this embodiment 1, by detecting the start timing of the voltage change between the output terminals of the switching element, the pre-charge period can be extended until just before the start of the voltage change between the output terminals of the switching element.

[0035] Furthermore, as shown in Figure 4, when both switching elements constituting the arm pair are in the off state, the current flowing in from the load side flows through the parasitic diodes of the switching elements. In this case, conduction losses occur in the parasitic diodes. In this embodiment 1, by shortening the switching delay of the switching elements, the period during which both switching elements are off is shortened, and conduction losses in the parasitic diodes are reduced.

[0036] Furthermore, by shortening the switching delay of the switching elements, the responsiveness of the switching elements to changes in the PWM signal's on / off state is improved. This allows for more efficient control of motors and other devices.

[0037] Furthermore, in the electronic circuit 100 according to this embodiment 1, when the first detection circuit 110 detects the completion timing of the voltage change between the output terminals of the switching element 11 while the second drive current Ig2 is being output, the control circuit 140 switches the drive current output from the current output circuit 130 to a third drive current Ig3 which is larger than the second drive current Ig2. Due to this feature, the electronic circuit 100 according to this embodiment 1 can shorten the post-charge period.

[0038] Furthermore, the first detection circuit 110 of the electronic circuit 100 according to this embodiment 1 detects the start timing of the voltage change between the output terminals of the switching element 11 by detecting the timing when the voltage Vds between the drain and source of the switching element 11 becomes equal to a predetermined first threshold voltage Vth1. Similarly, the second detection circuit 120 of the electronic circuit 100 according to this embodiment 1 detects the completion timing of the voltage change between the output terminals of the switching element 11 by detecting the timing when the voltage Vds between the drain and source of the switching element 11 becomes equal to a predetermined second threshold voltage Vth2. With these features, the electronic circuit 100 according to this embodiment 1 can easily and accurately detect the start and completion timing of the voltage change between the output terminals of the switching element 11.

[0039] (Embodiment 2) Next, an electronic circuit 200 according to Embodiment 2 will be described. In the electronic circuit 100 according to Embodiment 1 described above, the drive current was switched at the timing when the start or completion of the voltage change between the output terminals of the switching element 11 was detected. However, depending on the operating speed of the electronic circuit and the switching element, the switch of the drive current at the timing of the start or completion of the voltage change between the output terminals of the switching element may not be fast enough.

[0040] In the electronic circuit 200 according to this second embodiment, the drive current can be reliably switched at the start or completion timing of the voltage change between the output terminals of the switching element, regardless of the operating speed of the electronic circuit and the switching element.

[0041] Figure 5 shows the internal configuration of the electronic circuit 200 according to this second embodiment. In addition to the components of the electronic circuit 100 according to the first embodiment described above, the electronic circuit 200 includes a measurement circuit 250, a first memory circuit 251, and a second memory circuit 252. Furthermore, the electronic circuit 200 includes a control circuit 240 instead of the control circuit 140.

[0042] The measurement circuit 250 measures a third time T3 from the time the first detection circuit 110 detects the start timing of the voltage change between the output terminals of the switching element 11 until the second detection circuit 120 detects the completion timing of the voltage change between the output terminals of the switching element 11. More specifically, the measurement circuit 250 measures the third time T3 based on the number of system clocks counted from the time the first detection circuit 110 detects the start timing of the voltage change between the output terminals until the second detection circuit 120 detects the completion timing of the voltage change between the output terminals.

[0043] The first memory circuit 251 stores the first time T1 at which the first drive current Ig1 is supplied by the current output circuit 130. The second memory circuit 252 stores the second time T2 at which the second drive current Ig2 is supplied by the current output circuit 130. In this embodiment 2, the second time T2 is a predetermined fixed value.

[0044] The control circuit 240, in response to the rising edge of the PWM signal, causes the current output circuit 130 to start outputting a first drive current Ig1, and then controls the magnitude of the drive current output from the current output circuit 130 based on a first time T1 stored in the first memory circuit 251 and a second time T2 stored in the second memory circuit 252. The control circuit 240 also modifies the value of the first time T1 stored in the first memory circuit 251 based on a third time T3 measured by the measurement circuit 250 at a predetermined period different from the period of the PWM signal, for example every 1ms.

[0045] Figure 6 is a timing chart illustrating the operation of the switching element 11 driven by the drive current output from the current output circuit 130 and the drive current output from the current output circuit 130.

[0046] When the rising edge of the PWM signal is detected during a certain period of the PWM signal (time t1), the control circuit 240 causes the current output circuit 130 to start outputting the first drive current Ig1 (time t2).

[0047] After the current output circuit 130 starts outputting the first drive current Ig1, and after a first time T1 stored in the first memory circuit 251 has elapsed, the control circuit 240 switches the drive current output from the current output circuit 130 from the first drive current Ig1 to the second drive current Ig2 (time t3).

[0048] After the current output circuit 130 starts outputting the first drive current Ig2, and after a second time T2 stored in the second memory circuit 252 has elapsed, the control circuit 240 switches the drive current output from the current output circuit 130 from the second drive current Ig2 to the third drive current Ig3 (time t4).

[0049] Furthermore, at a predetermined period different from the period of the PWM signal, for example every 1 ms, the measurement circuit 250 measures a third time T3 from the time the start timing of the voltage change between the output terminals of the switching element 11 is detected by the first detection circuit 110 until the completion timing of the voltage change between the output terminals of the switching element 11 is detected by the second detection circuit 120. Based on the third time T3 measured by the measurement circuit 250, the control circuit 240 corrects the value of the first time T1 stored in the first memory circuit 251.

[0050] In detail, if the difference between the second time T2 and the third time T3 is greater than 0, i.e., T2-T3>0, then the first time T1 for which the first drive current Ig1 is supplied is too short, causing the timing of the switch from the first drive current Ig1 to the second drive current Ig2 to occur earlier than the start timing of the voltage change between the output terminals. In this case, the control circuit 240 increases the first time T1 stored in the first memory circuit 251 by a predetermined time ΔT. For example, the predetermined time ΔT is set to the minimum time resolution of the measurement circuit 250.

[0051] On the other hand, if the difference between the second time T2 and the third time T3 is 0 or less, i.e., T2-T3≦0, then the first time T1 during which the first drive current Ig1 is supplied is too long, causing the timing of the switch from the first drive current Ig1 to the second drive current Ig2 to be later than the start timing of the voltage change between the output terminals. In this case, the control circuit 240 reduces the first time T1 stored in the first memory circuit 251 by a predetermined time ΔT.

[0052] Thereafter, at predetermined intervals different from the PWM signal period, for example every 1ms, the control circuit 240 modifies the value of the first time T1 stored in the first memory circuit 251 based on a third time T3 measured by the measurement circuit 250. As a result, the first time T1 at which the first drive current g1 is output converges to an appropriate value, and the timing of the switch from the first drive current Ig1 to the second drive current Ig2 becomes equal to the start timing of the voltage change between the output terminals.

[0053] As described above, the control circuit 240 of the electronic circuit 200 according to this second embodiment switches the drive current output from the current output circuit 130 from the first drive current Ig1 to the second drive current Ig2 after a first time T1 has elapsed since the current output circuit 130 started outputting the first drive current Ig1, and outputs the second drive current Ig2 for a second time T2.

[0054] Furthermore, at predetermined intervals different from the PWM signal period, for example every 1ms, the control circuit 240 modifies the value of the first time T1 stored in the first memory circuit 251 based on a third time T3 measured by the measurement circuit 250. This ensures that the drive current switching at the start timing of the voltage change between the output terminals of the switching element is reliably performed, regardless of the operating speed of the electronic circuit and the switching element.

[0055] (Embodiment 3) Next, an electronic circuit 300 according to Embodiment 3 will be described. In the electronic circuit 300 according to Embodiment 3, the value of the second drive current Ig2 is modified based on the third time T3 required from the start to the completion of the voltage change between the output terminals of the switching element 11.

[0056] Figure 7 shows the internal configuration of the electronic circuit 300 according to this third embodiment. In addition to the components of the electronic circuit 200 according to the second embodiment described above, the electronic circuit 300 includes a third memory circuit 353. The third memory circuit 353 stores the value of the second drive current Ig2 output by the current output circuit 130. Furthermore, the electronic circuit 300 includes a control circuit 340 instead of the control circuit 240.

[0057] Similar to Embodiment 2 described above, at a predetermined period different from the period of the PWM signal, for example every 1 ms, the measurement circuit 250 measures a third time T3 from the time the first detection circuit 110 detects the start timing of the voltage change between the output terminals of the switching element 11 until the second detection circuit 120 detects the completion timing of the voltage change between the output terminals of the switching element 11. Based on the third time T3 measured by the measurement circuit 250, the control circuit 340 corrects the value of the second drive current Ig2 stored in the memory circuit 353.

[0058] In detail, if the third time T3 is shorter than a predetermined target time Ttg, the control circuit 340 reduces the second drive current Ig2. On the other hand, if the third time T3 is longer than the target time Ttg, the control circuit 340 increases the second drive current Ig2.

[0059] As mentioned above, the third time T3 required from the start to the completion of the voltage change between the output terminals of the switching element 11 depends on the value of the second drive current Ig2. Specifically, the larger the second drive current Ig2, the shorter the third time T3 required from the start to the completion of the voltage change between the output terminals can be. However, if the second drive current Ig2 is made too large, it can cause noise due to the rapid time change of the drain-source voltage Vds. Therefore, it is preferable that the third time T3 be as short as possible within the range where noise is not generated.

[0060] In this third embodiment, by experimentally or theoretically determining the shortest predetermined target time Ttg within the noise-free range, the third time T3 can be made as short as possible within the noise-free range. Therefore, the time required from the start to the completion of the voltage change between the output terminals of the switching element can be made as short as possible within the noise-free range.

[0061] (modified version) In the embodiments 1 to 3 described above, the three-phase inverter circuit 10 was configured using switching elements 11a to 11f. Alternatively, for example, the converter circuit may be configured using switching elements and diodes.

[0062] Furthermore, the switching elements 11a to 11f are not limited to MOSFETs. For example, the switching elements 11a to 11f may be IGBTs. Alternatively, the switching elements 11a to 11f may be BJTs (Bipolar Junction Transistors).

[0063] Furthermore, various materials such as Si (Silicon), SiC (Silicon Carbide), or GaN (Gallium Nitride) can be used as semiconductors constituting the switching elements 11a to 11f.

[0064] While several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the embodiments. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations are possible without departing from the spirit of the embodiments. These embodiments and their variations are included in the scope and spirit of the embodiments, as well as in the claims and their equivalents.

[0065] Furthermore, this embodiment can also be configured as follows. [Item 1] (Actual 1, Actual 2, Actual 3) A current output circuit that outputs a drive current to a switching element, A first detection circuit for detecting the start timing of the voltage change between the output terminals of the switching element, A control circuit that causes the current output circuit to start outputting a first drive current in response to a command signal that instructs the switching operation of the switching element, Equipped with, The control circuit is an electronic circuit that switches the drive current output from the current output circuit to a second drive current smaller than the first drive current, based on the start timing of a voltage change between the output terminals detected by the first detection circuit. [Item 2] (Actual 1) The electronic circuit according to item 1, wherein when the first detection circuit detects the start timing of a voltage change between the output terminals, the control circuit switches the drive current output from the current output circuit to the second drive current. [Item 3] (Actual 1) The first detection circuit is an electronic circuit according to item 1 or 2, which detects the start timing of a voltage change between the output terminals by detecting the timing at which the voltage between the output terminals of the switching element becomes equal to a predetermined first threshold voltage. [Item 4] (Practical 1) The electronic circuit according to item 3, wherein the first threshold voltage is set to a voltage within the range of 90% to 80% of the voltage between the output terminals when the switching element is not conducting. [Item 5] (Practical 1) The circuit further comprises a second detection circuit for detecting the completion timing of the voltage change between the output terminals of the switching element, The electronic circuit according to any one of items 2 to 4, wherein when the completion timing of the voltage change between the output terminals is detected by the second detection circuit, the control circuit switches the drive current output from the current output circuit to a third drive current that is larger than the second drive current. [Item 6] (Practical 1) The electronic circuit described in item 5, wherein the second detection circuit detects the completion timing of the voltage change between the output terminals by detecting the timing when the voltage between the output terminals of the switching element becomes equal to a predetermined second threshold voltage. [Item 7] (Practical 1) The electronic circuit according to item 6, wherein the second threshold voltage is set to a voltage within the range of 20% to 10% of the voltage between the output terminals when the switching element is not conducting. [Item 8] (Actual 2, Actual 3) A second detection circuit for detecting the completion timing of the voltage change between the output terminals of the switching element, A measurement circuit measures a third time from the time the first detection circuit detects the start timing of the voltage change between the output terminals until the second detection circuit detects the completion timing of the voltage change between the output terminals. Furthermore, The control circuit, after a first time has elapsed since the current output circuit started outputting the first drive current, switches the drive current output from the current output circuit from the first drive current to the second drive current, outputs the second drive current for a second period of time, and corrects the value of the first time T1 based on the third time measured by the measurement circuit, as described in item 1. [Item 9] (Actual 2, Actual 3) The control circuit described in item 8 increases the first time by a predetermined amount of time when the difference between the second time and the third time is greater than 0, and decreases the first time by the predetermined amount of time when the difference between the second time and the third time is 0 or less. [Item 10] (Actual 3) The control circuit is an electronic circuit according to item 8 or 9 that modifies the value of the second drive current based on the third time. [Item 11] (Actual 3) The control circuit, according to item 10, reduces the second drive current when the third time is shorter than a predetermined target time, and increases the second drive current when the third time is longer than the target time. [Item 12] Two switching elements constitute the arm pair, Two electronic circuits that supply drive current to the two switching elements, respectively. A power conversion device including, Each of the aforementioned electronic circuits is, A current output circuit that outputs a drive current to the switching element, A first detection circuit for detecting the start timing of the voltage change between the output terminals of the switching element, A control circuit that causes the current output circuit to start outputting a first drive current in response to a command signal that instructs the switching operation of the switching element, Equipped with, The control circuit is a power converter that switches the drive current output from the current output circuit to a second drive current smaller than the first drive current, based on the start timing of a voltage change between the output terminals detected by the first detection circuit. [Item 13] A power conversion circuit having two switching elements that constitute an arm pair connected to a load, and three sets of two electronic circuits that supply drive current to each of the two switching elements. An inverter including, Each of the aforementioned electronic circuits is, A current output circuit that outputs a drive current to the switching element, A first detection circuit for detecting the start timing of the voltage change between the output terminals of the switching element, A control circuit that causes the current output circuit to start outputting a first drive current in response to a command signal that instructs the switching operation of the switching element, Equipped with, The control circuit is an inverter that switches the drive current output from the current output circuit to a second drive current smaller than the first drive current, based on the start timing of the voltage change between the output terminals detected by the first detection circuit. [Explanation of Symbols]

[0066] 1. Motor control system 2 Motors (Load) 3 DC power supply 4. Detection Circuit 5 Signal supply circuit 10 Inverter Circuit 11 Switching elements 100 electronic circuits 110 First detection circuit 111 Comparator 112 Voltage source 113 Detection signal output circuit 120 Second detection circuit 121 Comparator 122 Voltage Source 123 Detection signal output circuit 130 Current Output Circuit 140 Control circuits 200 Electronic circuits 240 Control circuits 250 measurement circuit 251 First memory circuit 252 Second Memory Circuit 300 Electronic circuits 340 Control circuits 353 Third Memory Circuit T1 First period T2 Second Period T3 Third Time Ttg target time Id drain current Ig1 First drive current Ig2 Second drive current Ig3 Third drive current Vds: Drain-source voltage (voltage between output terminals) Vg gate voltage Vth1 First threshold voltage Vth2 Second threshold voltage

Claims

1. A current output circuit that outputs a drive current to a switching element, A first detection circuit for detecting the start timing of the voltage change between the output terminals of the switching element, A control circuit that causes the current output circuit to start outputting a first drive current in response to a command signal that instructs the switching operation of the switching element, A second detection circuit for detecting the completion timing of the voltage change between the output terminals of the switching element, A measurement circuit measures a third time from the time the first detection circuit detects the start timing of the voltage change between the output terminals until the second detection circuit detects the completion timing of the voltage change between the output terminals. Equipped with, The control circuit switches the drive current output from the current output circuit to a second drive current smaller than the first drive current, based on the start timing of the voltage change between the output terminals detected by the first detection circuit. When a first time has elapsed since the current output circuit started outputting the first drive current, the current output circuit switches the drive current output from the first drive current to the second drive current, and outputs the second drive current for a second period of time. Based on the third time measured by the measurement circuit, the value of the first time is corrected. electronic circuit.

2. The electronic circuit according to claim 1, wherein when the first detection circuit detects the start timing of a voltage change between the output terminals, the control circuit switches the drive current output from the current output circuit to the second drive current.

3. The electronic circuit according to claim 1, wherein the first detection circuit detects the start timing of a voltage change between the output terminals by detecting the timing at which the voltage between the output terminals of the switching element becomes equal to a predetermined first threshold voltage.

4. The electronic circuit according to claim 3, wherein the first threshold voltage is set to a voltage within the range of 90% to 80% of the voltage between the output terminals when the switching element is not conducting.

5. The circuit further comprises a second detection circuit for detecting the completion timing of the voltage change between the output terminals of the switching element, The electronic circuit according to claim 2, wherein when the second detection circuit detects the completion timing of the voltage change between the output terminals, the control circuit switches the drive current output from the current output circuit to a third drive current that is larger than the second drive current.

6. The electronic circuit according to claim 5, wherein the second detection circuit detects the timing of completion of the voltage change between the output terminals by detecting the timing when the voltage between the output terminals of the switching element becomes equal to a predetermined second threshold voltage.

7. The electronic circuit according to claim 6, wherein the second threshold voltage is set to a voltage within the range of 20% to 10% of the voltage between the output terminals when the switching element is not conducting.

8. The electronic circuit according to claim 1, wherein the control circuit increases the first time by a predetermined amount of time when the difference between the second time and the third time is greater than zero, and decreases the first time by the predetermined amount of time when the difference between the second time and the third time is zero or less.

9. The electronic circuit according to claim 1, wherein the control circuit modifies the value of the second drive current based on the third time.

10. The electronic circuit according to claim 9, wherein the control circuit reduces the second drive current when the third time is shorter than a predetermined target time, and increases the second drive current when the third time is longer than the target time.

11. Two switching elements constitute the arm pair, Two electronic circuits that supply drive current to the two switching elements, respectively. A power conversion device including, Each of the aforementioned electronic circuits is, A current output circuit that outputs a drive current to the switching element, A first detection circuit for detecting the start timing of the voltage change between the output terminals of the switching element, A control circuit that causes the current output circuit to start outputting a first drive current in response to a command signal that instructs the switching operation of the switching element, A second detection circuit for detecting the completion timing of the voltage change between the output terminals of the switching element, A measurement circuit measures a third time from the time the first detection circuit detects the start timing of the voltage change between the output terminals until the second detection circuit detects the completion timing of the voltage change between the output terminals. Equipped with, The control circuit switches the drive current output from the current output circuit to a second drive current smaller than the first drive current, based on the start timing of the voltage change between the output terminals detected by the first detection circuit. When a first time has elapsed since the current output circuit started outputting the first drive current, the current output circuit switches the drive current output from the first drive current to the second drive current, and outputs the second drive current for a second period of time. Based on the third time measured by the measurement circuit, the value of the first time is corrected. Power converter.

12. A power conversion circuit having three sets of two switching elements that constitute an arm pair connected to a load, and two electronic circuits that supply drive current to each of the two switching elements. An inverter including, Each of the aforementioned electronic circuits is, A current output circuit that outputs a drive current to the switching element, A first detection circuit for detecting the start timing of the voltage change between the output terminals of the switching element, A control circuit that causes the current output circuit to start outputting a first drive current in response to a command signal that instructs the switching operation of the switching element, A second detection circuit for detecting the completion timing of the voltage change between the output terminals of the switching element, A measurement circuit measures a third time from the time the first detection circuit detects the start timing of the voltage change between the output terminals until the second detection circuit detects the completion timing of the voltage change between the output terminals. Equipped with, The control circuit switches the drive current output from the current output circuit to a second drive current smaller than the first drive current, based on the start timing of the voltage change between the output terminals detected by the first detection circuit. When a first time has elapsed since the current output circuit started outputting the first drive current, the current output circuit switches the drive current output from the first drive current to the second drive current, and outputs the second drive current for a second period of time. Based on the third time measured by the measurement circuit, the value of the first time is corrected. Inverter.

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