JP6906390B2 - Switching circuit - Google Patents

Description

The present invention relates to a switching circuit that drives a plurality of switches connected in parallel.

In a switching circuit used in an in-vehicle power converter or the like, for example, in order to meet the demand for higher power consumption, a configuration is adopted in which a plurality of switches connected in parallel are simultaneously turned on and off. In this configuration, there is a problem that the switching loss is biased due to the deviation of the switching timing due to the variation in the characteristics of the individual semiconductor switching elements constituting the switch.

On the other hand, a method of controlling the switching timing by detecting the characteristic difference of a plurality of semiconductor switching elements has been proposed. For example, in Patent Document 1, in a power conversion device in which a plurality of semiconductor modules incorporating a semiconductor switching element and a temperature detection element are connected in parallel and used, the temperature detection element of each semiconductor module is used in the control circuit of the semiconductor switching element. It is described that a circuit for detecting the difference or magnitude of the detected value and a circuit for delaying the turn-on command signal to the semiconductor switching element on the side where the detection temperature is high are provided.

JP-A-2009-159662

In the method described in Patent Document 1, the temperatures of the two semiconductor switching elements are compared, and the on-timing of the semiconductor switching element having a high temperature is delayed to suppress the current bias. However, this method requires a plurality of drive circuits and delay circuits corresponding to each of the plurality of semiconductor modules in order to delay one of the hot turn-on command signals. Further, in order to make the delay time variable, each delay circuit needs to be a circuit including a plurality of capacitors having different capacitances. Therefore, it is not always easy to give a delay time according to the temperature difference and align the switching timings. Alternatively, the circuit configuration becomes complicated, and the manufacturing cost increases due to the increase in the number of parts.

The present invention has been made in view of the above problems, and in a switching circuit for driving a plurality of switches connected in parallel, a bias in switching loss due to characteristic variation or the like is suppressed while suppressing a cost increase due to a complicated circuit configuration. This is an attempt to provide a compact and low-loss switching circuit that can suppress the above.

One aspect of the present invention is
A drive circuit (2) for driving a plurality of switches (S1, S2) connected in parallel, and
A switch timing compensation circuit (3) connected between the drive circuit and the gate terminals of one or more of the switches.
It is equipped with a temperature detection circuit (4) as a physical information detection circuit that detects temperature information as physical information that correlates with the switch characteristics of the above switch.
The switch timing compensation circuit includes bias capacitors (C1, C2) provided on gate wires (11p, 12p) connecting the gate terminal of the corresponding switch and the drive circuit, and a bias for charging the bias capacitor. A control circuit that controls the voltage of the bias power supply based on the power supply (V1, V2), the diodes (D1, D2) connected in series with the bias power supply, and the temperature information detected by the temperature detection circuit. Has (5, 51, 52) and
The diode has a configuration in which the cathode side is connected to the gate wire, the anode side is connected to the bias power supply, and the bias capacitor is charged via the diode.
The control circuit, the comparison result of the temperature information corresponding to a plurality of the switch, or, based on a result of comparison between the temperature information of the corresponding the switch and the reference temperature, the voltage of the bias power supply, the comparison result It is in a switching circuit that adjusts so that the difference in switch timing of a plurality of the above-mentioned switches known from is small.

In the switching circuit of the above aspect, the switch timing compensation circuit is provided for at least one of the plurality of switches, and the bias voltage charged in the bias capacitor can be applied to the gate terminal thereof. If the threshold voltage at which multiple switches are turned on varies due to individual differences or changes over time, the on-timing shift will occur. Using the physical information that correlates with this characteristic shift, the charge amount of the bias capacitor can be determined. Can be adjusted. For example, among a plurality of switches, for a switch having a characteristic that the on-timing is delayed, a bias voltage corresponding to a detected value of physical information is added, so that the timing of reaching the threshold voltage can be aligned. .. Therefore, the bias of the switching loss can be suppressed, and the overall loss can be reduced.

As described above, according to the above aspect, in a switching circuit for driving a plurality of switches connected in parallel, it is possible to suppress a bias in switching loss due to characteristic variation or the like while suppressing a cost increase due to a complicated circuit configuration. It is possible to provide a small and low loss switching circuit.
The reference numerals in parentheses described in the scope of claims and the means for solving the problem indicate the correspondence with the specific means described in the embodiments described later, and limit the technical scope of the present invention. It's not a thing.

The circuit diagram which shows the whole structure of the switching circuit in Embodiment 1. The circuit diagram which shows the whole structure of the modification of the switching circuit in Embodiment 1. The circuit diagram which shows the main part structure of the modification of the switching circuit in Embodiment 1. The circuit diagram for demonstrating the basic operation of the switching circuit in Embodiment 1. The waveform diagram which shows the relationship between each switch on / off timing of a switching circuit, and a switching loss in Embodiment 1. FIG. The circuit diagram which shows the current path at the time of each switch of a switching circuit in Embodiment 1. FIG. The equivalent circuit diagram at the time of off which shows the composition of the main part of the switching circuit in Embodiment 1. FIG. The equivalent circuit diagram at the time of on which shows the composition of the main part of the switching circuit in Embodiment 1. FIG. The circuit diagram which shows the main part structure of the switching circuit in Embodiment 2. The circuit diagram which shows the current path at the time of turning on each switch of a switching circuit in Embodiment 2. The equivalent circuit diagram at the time of off which shows the composition of the main part of the switching circuit in Embodiment 2. The block diagram which shows the other control example in the switch timing compensation circuit of the switching circuit in Embodiment 3. FIG. The block diagram which shows the other control example in the switch timing compensation circuit of the switching circuit in Embodiment 3. FIG. The block diagram which shows the other control example in the switch timing compensation circuit of the switching circuit in Embodiment 3. FIG. The circuit diagram which shows the whole structure of the switching circuit in Embodiment 4. The circuit diagram which shows the main part structure of the switching circuit in Embodiment 4. The circuit diagram which shows the main part structure of the modification of the switching circuit in Embodiment 4. The circuit diagram which shows the main part structure of the modification of the switching circuit in Embodiment 4. The circuit diagram which shows the main part structure of the switching circuit in Embodiment 5. The circuit diagram which shows the main part structure of the modification of the switching circuit in Embodiment 5.

(Embodiment 1)
Hereinafter, the first embodiment relating to the switching circuit will be described with reference to FIGS. 1 to 8.
As shown in FIG. 1, the switching circuit 1 of the present embodiment includes a plurality of switches S1 and S2 connected in parallel, a common drive circuit 2 for driving the plurality of switches S1 and S2, and a switch timing compensation circuit 3. And a temperature detection circuit 4 as a physical information detection circuit that detects physical information that correlates with the switch characteristics of the switches S1 and S2. The switch timing compensation circuit 3 is connected between the drive circuit 2 and the gate terminals of at least one of the switches S1 and S2.

Specifically, the switch timing compensation circuit 3 has bias capacitors C1 and C2 and variable biases V1 and V2, which are bias power supplies for charging the bias capacitors C1 and C2. , Is provided for each of the switches S1 and S2. The switch timing compensation circuit 3 adjusts the voltage of the bias power supply based on the temperature information which is the physical information detected by the temperature detection circuit 4 so that the difference between the switch timings of the plurality of switches S1 and S2 becomes small. Therefore, the switch timing compensation circuit 3 can be provided with a control circuit 5 that performs control based on temperature information. Here, control circuits 51 and 52 for giving a control command based on temperature information (for example, a bias power supply voltage command value) to the variable biases V1 and V2 are provided, respectively.

The switching circuit 1 is applied to, for example, an in-vehicle motor inverter device or the like, which is an in-vehicle power conversion device. In that case, the inverter device has, for example, a configuration in which a plurality of half bridge circuits corresponding to each phase (that is, U phase, V phase, W phase) of the three-phase motor are connected in parallel, and the half of each phase. The bridge circuit is driven on and off at different timings to convert DC power into three-phase AC power. Each of the plurality of half-bridge circuits is composed of a series connection of an upper arm switch and a lower arm switch, and when one of the lower arm switch and the upper arm switch is in the on state, the other is in the off state. Further, the lower arm switch or the upper arm switch of each half-bridge circuit may have a configuration in which a plurality of switches are connected in parallel. The switching circuit 1 is configured as a circuit for driving each switch of such a half-bridge circuit.

The switching circuit 1 in this embodiment is configured as a drive circuit on the lower arm side of the half-bridge circuit. For example, two switches S1 and S2 are provided as a plurality of lower arm switches connected in parallel. The switches S1 and S2 are, for example, gate voltage controlled MOSFETs (that is, field effect transistors), and n-channel MOSFETs are used here. As the semiconductor switching element, a semiconductor power element other than the MOSFET, for example, an IGBT (insulated gate bipolar transistor) or the like can also be used. When an IGBT is used, the base terminal of the IGBT is referred to as a gate terminal like the MOSFET.

In FIG. 1, the switches S1 and S2 are connected in parallel between the positive electrode terminal and the negative electrode terminal of the power supply B (for example, the power supply voltage Vi). That is, the positive electrode terminal of the power supply B is connected to the drain terminal of the switches S1 and S2 via the resistor R, and the negative electrode terminal of the power supply B is connected to the source terminal of the switches S1 and S2. A drive circuit 2 is connected between the gate terminal and the source terminal of the switches S1 and S2 via the switch timing compensation circuit 3. Here, the configuration has two switches S1 and S2, but it may have three or more switches, and even in that case, one drive circuit 2 is provided in common to all the switches.

The drive circuit 2 outputs a pulsed gate signal to switch the switches S1 and S2 on and off. The drive circuit 2 is composed of, for example, a gate power supply B1 (for example, a power supply voltage Vgs), an on drive switch 21 of the gate power supply B1, and an off drive switch 22 of the gate power supply B1, and is alternately turned on and off. To generate a predetermined pulse. The off drive switch 22 is provided between the positive electrode terminal and the negative electrode terminal of the gate power supply B1, and the on drive switch 21 is provided between the positive electrode terminal and the off drive switch 22 of the gate power supply B1.

The switch timing compensation circuit 3 has a bias capacitor C1 provided on the gate wire 11p and a variable bias V1 for charging the bias capacitor C1 on the switch S1 side. Similarly, the switch S2 side also has a bias capacitor C2 provided on the gate wire 12p and a variable bias V2 for charging the bias capacitor C2. The gate wires 11p and 12p are connected to the cathode sides of the rectifying diodes D1 and D2 between the bias capacitors C1 and C2 and the switches S1 and S2, respectively. One end side of the variable bias V1 and V2 is connected in series to the anode side of the diodes D1 and D2, respectively. The other ends of the variable biases V1 and V2 are connected to the source terminals of the switches S1 and S2 via the source lines 11n and 12n, respectively.

Further, discharge resistors R1 and R2 for discharging the bias capacitors C1 and C2 are connected between the gate wire 11p and the source wire 12n and between the gate wire 12p and the source wire 12n. The discharge resistors R1 and R2 make it easy to reset the voltage of the bias capacitors C1 and C2. The resistance for voltage reset can be substituted by the pattern resistance, the on resistance of the switches 21 and 22 in the drive circuit 2, and the gate resistance of the switches S1 and S2. In that case, the discharge resistors R1 and R2 are not necessarily the same. There is no need to provide it.

The temperature detection circuit 4 includes temperature sensors 41 and 42 that detect the respective temperatures as one of the physical information that correlates with the switch characteristics of the switches S1 and S2. If a shift occurs in the switch timing when the gate voltage is applied to the switches S1 and S2, for example, the calorific value of the switches S1 and S2 changes, so that the shift in the switch characteristics can be detected as a temperature difference. As the temperature sensors 41 and 42, for example, existing temperature sensors built in the semiconductor modules constituting the switches S1 and S2 can be used.

The control circuits 51 and 52 are connected to the variable biases V1 and V2, respectively, and one or both of them can be operated based on the detection result of the temperature detection circuit 4. The detection values of the two temperature sensors 41 and 42 are input to the control circuits 51 and 52, respectively, and the difference between the detected values is preferably 0 so that the difference between the detected values becomes small. As described above, the bias power supply voltage command value is output to the variable biases V1 and V2.
The control of the variable biases V1 and V2 using the control circuits 51 and 52 will be described later.

As shown in FIG. 2 as a modification of the first embodiment, the smoothing capacitor Cb1 and the discharge resistor Rb1 for discharging the smoothing capacitor Cb1 are connected in parallel to the variable bias V1 on the switch S1 side. You can also. Similarly, the smoothing capacitor Cb2 and the discharge resistor Rb2 for discharging the smoothing capacitor Cb2 can be connected in parallel to the variable bias V2 on the switch S2 side. One end side of the smoothing capacitors Cb1 and Cb2 and the discharge resistors Rb1 and Rb2 is connected to the connection point between the diodes D1 and D2 and the variable bias V1 and V2, and the other end side is the switch S1 via the source wires 11n and 12n. , S2 is connected to the source terminal.

By providing the smoothing capacitors Cb1 and Cb2, the voltage between both ends of the variable bias V1 and V2 can be smoothed, and the bias voltage can be controlled stably. Further, the discharge resistors Rb1 and Rb2 can easily reset the voltage of the smoothing capacitors Cb1 and Cb2.
The configuration of the other switch timing compensation circuit 3 including the control circuits 51 and 52, the configuration of the drive circuit 2, and the configuration of the temperature detection circuit 4 are the same as those of the switching circuit 1 shown in FIG. 1, and the description thereof will be omitted.

In FIGS. 1 and 2, the variable biases V1 and V2 are variable voltage power supplies, and are adjusted to a desired voltage based on the voltage command values from the control circuits 51 and 52. The detection values of the two temperature sensors 41 and 42 are input to the control circuits 51 and 52, respectively, and the difference between the detected values is preferably 0 so that the difference between the detected values becomes small. As described above, the voltage command value is output to the variable biases V1 and V2. The switch timing compensation circuit 3 operates one or both of the control circuits 51 and 52, outputs a voltage command value based on the detection result of the temperature detection circuit 4, and outputs a voltage command value based on the detection result of the temperature detection circuit 4, and either one of the variable biases V1 and V2, Or both can be operated.

Next, the circuit operation of the switching circuit 1 in this embodiment will be described.
FIG. 3 is a part of the configuration shown in the modified example of FIG. 2, and shows only the switch timing compensation circuit 3 on the switch S2 side among the switches S1 and S2. Hereinafter, as an example, control for adjusting the switch timing on the switch S2 side having a lower temperature among the switches S1 and S2 to match the switch timing on the switch S2 side having a higher temperature will be described.

As shown in FIGS. 4 and 5 as a basic operation example of the switch timing compensation circuit 3, even if a gate signal is output from the drive circuit 2 to the two switches S1 and S2 at the same time, the two switches S1 and S2 If there is a deviation between the threshold voltages Vth_S1 and Vth_S2, the on / off timings do not coincide. For example, as in the conventional example shown on the left side of FIG. 5, the on timing of the switch S1 having a lower threshold voltage Vth_S1 is earlier than that of the switch S2, and the off timing of the switch S1 is later than that of the switch S2. Therefore, as shown in FIG. 6, it is desirable that the two switches S1 and S2 connected in parallel are turned on at the same time and the current I from the power supply B is evenly distributed (for example, I =). I1 + I2), the time that only the switch S1 is turned on becomes longer. As a result, the current is biased when it is turned on and when it is turned off, and the switching loss increases.

Further, due to this bias of the current, the temperature of the switch S1 becomes higher than the temperature of the switch S2. Therefore, as shown in the right figure of FIG. 5, the on-timing of the switch S2 is performed by applying the bias voltage Vbias to the gate voltage waveform of the switch S2 having a higher threshold voltage Vth_S2 according to the temperature difference between the switches S1 and S2. Can be accelerated. Further, the off timing of the switch S2 can be delayed. Specifically, the temperature difference between the switches S1 and S2 reflecting the difference between the threshold voltages Vth_S2 and Vth_S1 is detected by using the two temperature sensors 41 and 42, and the error voltage compared by the control circuit 52 is amplified. , The voltage command value to the variable bias V2 can be used. Then, the bias capacitor C2 can be charged by the variable bias V2 to adjust the gate drive voltage.

FIG. 7 is an equivalent circuit when the circuit shown in FIG. 3 is off, in which the on drive switch 21 of the drive circuit 2 is off and the off drive switch 22 is on. For example, when the power supply voltage of the variable bias V2 is a predetermined voltage Vc according to the bias power supply voltage command value, an electric charge is supplied to the gate wire 12p from the variable bias V2 via the diode D2, and the bias capacitor C2 It will be charged. The voltage of the bias capacitor C2 is Vc−Vf obtained by subtracting the voltage Vf of the forward voltage drop of the diode D2. As a result, a bias voltage Vbias of Vc-Vf can be applied between the gate and source of the switch S2.

Next, as shown in FIG. 8 as an equivalent circuit at the time of on, the on drive switch 21 of the drive circuit 2 is turned on and the off drive switch 22 is turned off. At this time, in addition to the bias voltage Vbias of Vc-Vf, the power supply voltage Vgs is applied from the gate power supply B1 of the drive circuit 2 between the gate and source of the switch S2. Therefore, as shown in the right figure of FIG. 5, since the bias voltage Vbias is added to the switch S2 while keeping the gate voltage waveform as it is, the timing of reaching the threshold voltage Vth_S2 can be aligned with the switch S1.

Similarly, when the threshold voltage Vth_S2 of the switch S1 is higher, the same effect can be obtained by performing switch timing compensation on the switch S1 side using the control circuit 51. In this way, by applying the bias voltage Vbias to the immediate vicinity of the gates of the switches S1 and S2, the switching timing can be made uniform. Then, the bias of the switching loss is eliminated, the temperature difference between the switches S1 and S2 is eliminated, and the overall loss can be reduced.

(Embodiment 2)
The second embodiment according to the switching circuit will be described with reference to FIGS. 9 to 11.
As shown in FIG. 9, the basic configuration of the switching circuit 1 of this embodiment is the same as that of the first embodiment, for driving a plurality of switches S1 and S2 connected in parallel and a plurality of switches S1 and S2. It includes a drive circuit 2, a switch timing compensation circuit 3, and a temperature detection circuit 4 as a physical information detection circuit. The switch timing compensation circuit 3 is connected between the drive circuit 2 and the gate terminals of at least one of the switches S1 and S2. Hereinafter, the differences will be mainly described.
In addition, among the codes used in the second and subsequent embodiments, the same codes as those used in the above-described embodiments represent the same components and the like as those in the above-mentioned embodiments, unless otherwise specified.

In the first embodiment, the case where the switches S1 and S2 connected in parallel are used as the lower arm switch of the half bridge circuit has been described. However, in the switching circuit 1 of the present embodiment, the plurality of switches S1 and S2 are used as the upper arm switch. It is used as. Further, here, only the switch timing compensation circuit 3 on the switch S1 side is shown, and a case where a bias voltage Vbias is applied to the switch S1 side by using the variable bias V1 and the bias capacitor C1 will be described, but the same applies to the switch S2 side. Is.

In this embodiment, the switch S1 which is the upper arm switch is connected in series with the switch S0 which is the lower arm switch, and the switch S0 is connected between the source terminal of the switch S1 and the negative electrode terminal of the power supply B. .. Further, a series circuit of the variable bias V1 and the second diode Db is formed between the diode D1 connected to the gate wire 11p of the switch S1 and the negative electrode terminal of the power supply B between the second diode Db and the variable bias V1. A series circuit is connected. The variable bias V1 is connected between the negative electrode terminal of the power supply B and the anode side of the second diode Db, and the anode side of the diode D1 is connected to the cathode side of the second diode Db. This series circuit constitutes a bootstrap circuit.

The configuration in which the switch timing compensation circuit 3 includes the bias capacitor C1 and its discharge resistor R1, the diode D1, the smoothing capacitor Cb1 and its discharge resistor Rb1 in addition to the bootstrap circuit is the same as that in the first embodiment. Then, the same effect can be obtained by inputting the detection values of the temperature sensors 41 and 42 of the temperature detection circuit 4 into the control circuit 51, outputting the voltage command value to the variable bias V1 and charging the bias capacitor C1. Be done.

As shown in FIG. 10 as an equivalent circuit at the time of off corresponding to FIG. 7, when the on drive switch 21 of the drive circuit 2 is off and the off drive switch 22 is on, the gate wire 11p has a variable bias V2 ( For example, electric charge is supplied from the voltage Vc) via the second diode Db and the diode D1 to charge the bias capacitor C1. At this time, the voltage of the bias capacitor C2 becomes Vc-2Vf obtained by subtracting the voltage Vf of the forward voltage drop of the second diode Db and the diode D2. As a result, a bias voltage Vbias of Vc-2Vf can be applied between the gate and source of the switch S2.

Next, as shown in FIG. 11 as an on-time equivalent circuit corresponding to FIG. 8, the on drive switch 21 of the drive circuit 2 is turned on and the off drive switch 22 is turned off. At this time, in addition to the bias voltage Vbias of Vc-2Vf, the power supply voltage Vgs is applied from the gate power supply B1 of the drive circuit 2 between the gate and source of the switch S1. Therefore, even in this embodiment, the bias voltage Vbias can be added while keeping the gate voltage waveform of the switch S1 as it is. In this way, one of the drive circuits 2 can be used to drive any of the control circuits 51 and 52 of the switch timing compensation circuit 3, and the timings at which the switches S1 and S2 reach the threshold voltages Vth_S1 and Vth_S2 can be aligned. ..

Also in this embodiment, the discharge resistor R1 for discharging the bias capacitor C1 can be replaced by the pattern resistor, the on-resistance of the switches 21 and 22 in the drive circuit 2, and the gate resistor of the switches S1 and S2. Further, the smoothing capacitor Cb1 and its discharge resistor Rb1 can be omitted.

(Embodiment 3)
12 to 14 show another control example that can be implemented by the control circuit 5 of the switch timing compensation circuit 3 in the switching circuit 1 of the first and second embodiments. In the control example described above, the bias voltage is added to either side of the switches S1 and S2 according to the detection result of the temperature detection circuit 4, but the variable biases V1 and V2 and the bias capacitors C1 and C2 are used. The bias voltage may be adjusted so that only one of the switches S1 and S2 is adjusted.

In this case, it is not necessary to provide the control circuits 51 and 52 corresponding to the switches S1 and S2, respectively, and the control example by the control circuit 5 will be described below. For example, as shown in FIG. 12, when only the adjustment on the switch S2 side is performed, first, the detection values (for example, voltage values) of the temperature sensors 41 and 42 of the temperature detection circuit 4 are taken in, and an error comparing the two is taken. Get the voltage. This error voltage is amplified by, for example, PI control, and the variable bias V2, which is a bias power supply, is controlled so that the voltage obtained by adding this amplified voltage to the initial voltage Vref becomes the bias power supply voltage.

At this time, a desired bias power supply voltage can be easily obtained by charging a voltage of about several V in advance as a reference initial voltage Vref and adding or subtracting the amplified portion of the error voltage corresponding to the temperature difference. That is, when the temperature on the switch S1 side is higher than the temperature on the switch S2 side, the error voltage of the temperature sensors 41 and 42 becomes positive, and the amplified portion is added to the initial voltage Vref. On the other hand, when the temperature on the switch S1 side is lower than the temperature on the switch S2 side, the error voltage becomes negative and the amplified component is subtracted from the initial voltage Vref.

In this way, the bias power supply voltage is increased or decreased with respect to the initial voltage Vref only on the switch S2 side, and control is performed to change the bias voltage so that the temperature difference due to the deviation of the threshold voltage becomes small, and this control is repeated. , The temperature difference between the switches S1 and S2 can be brought close to zero. As a result, switch timing compensation becomes possible by controlling the bias power supply of one of the switches S1 and S2.

As shown in FIG. 13, it is also possible to control the bias power supply voltage to be increased or decreased with respect to the initial voltage Vref for both the switches S1 and S2. Also in this case, first, the detection values (for example, voltage values) of the temperature sensors 41 and 42 of the temperature detection circuit 4 are taken into the control circuit 5, and the error voltage comparing the two is amplified by, for example, PI control. The bias power supply voltage command value is generated using this amplification voltage and the initial voltage Vref, and the variable biases V1 and V2, which are the bias power supplies, are controlled, respectively. The initial voltage Vref is charged with a voltage of about several V in advance, and the amplification of the error voltage corresponding to the temperature difference is added to the bias power supply voltage on one side and subtracted from the bias power supply voltage on the other side. do.

That is, when the temperature on the switch S1 side is higher than the temperature on the switch S2 side, the error voltage of the temperature sensors 41 and 42 becomes positive, the amplification component is subtracted from the initial voltage Vref on the switch S1 side, and on the switch S2 side. The amplified amount is added to the initial voltage Vref. On the other hand, when the temperature on the switch S1 side is lower than the temperature on the switch S2 side, the error voltage becomes negative, and the amplified component is subtracted from the initial voltage Vref on the switch S2 side. On the switch S1 side, the amplified amount is added to the initial voltage Vref.

In this way, in both the switches S1 and S2, the bias power supply voltage is increased or decreased with respect to the initial voltage Vref, and the bias voltage is controlled to be variable so that the influence of the deviation of the threshold voltage of the switches S1 and S2 is reduced. be able to. By repeating this control, the temperature difference between the switches S1 and S2 can be brought close to 0, and quicker switch timing compensation becomes possible.

As shown in FIG. 14, when the bias power supply voltage is increased or decreased for both the switches S1 and S2, the initial voltage Vref can be set as the maximum value and controlled so as not to exceed this. Also in this case, first, the detection values (for example, voltage values) of the temperature sensors 41 and 42 of the temperature detection circuit 4 are taken into the control circuit 5, and the error voltage comparing the two is amplified by PI control. Using this amplification voltage and the initial voltage Vref, the bias power supply voltage command values of the variable biases V1 and V2, which are the bias power supplies, are controlled. The initial voltage Vref is charged with a voltage of about several V in advance, the value is set as the maximum value, and the amplified portion of the error voltage corresponding to the temperature difference is subtracted for one of the switches S1 and S2.

That is, when the temperature on the switch S1 side is higher than the temperature on the switch S2 side, the error voltage of the temperature sensors 41 and 42 becomes positive, and the amplified component is subtracted from the initial voltage Vref on the switch S1 side. On the switch S2 side, the limiter prevents the amplified component from being added to the initial voltage Vref, and the bias power supply voltage is limited to the initial voltage Vref. On the other hand, when the temperature on the switch S1 side is lower than the temperature on the switch S2 side, the error voltage becomes negative, and the amplified component is subtracted from the initial voltage Vref on the switch S2 side. On the switch S1 side, the amplification component is prevented from being added to the initial voltage Vref, and the bias power supply voltage is limited to the initial voltage Vref.

In this way, the temperature difference between the switches S1 and S2 can be brought close to 0 by repeating the control of changing the bias power supply voltage based on the initial voltage Vref in both the switches S1 and S2. Further, in both the switches S1 and S2, by limiting the maximum value of the bias power supply voltage to the initial voltage Vref, the decrease of the dead time can be suppressed, and good switch timing compensation becomes possible.

(Embodiment 4)
The fourth embodiment according to the switching circuit will be described with reference to FIGS. 15 to 18.
As shown in FIG. 15, the basic configuration of the switching circuit 1 of this embodiment is the same as that of the first embodiment, for driving a plurality of switches S1 and S2 connected in parallel and a plurality of switches S1 and S2. It includes a drive circuit 2. Here, the switch timing compensation circuit 3 is connected between the drive circuit 2 and the gate terminals of the switches S1 and S2, and corresponds to the switches S1 and S2, and the bias capacitors C1, C2, the diodes D1 and D2. Are provided respectively.

In the switching circuit 1 of the first embodiment shown in FIG. 1, the temperature detection circuit 4 is provided separately from the switch timing compensation circuit 3, and the control circuit 5 is used to control the bias power supply voltage. The switch timing compensation circuit 3 includes a bias power supply voltage generation circuit 6 as a power supply voltage generator, which also serves as a bias power supply, a temperature detection circuit 4, and a control circuit 5. Here, the bias power supply voltage generation circuits 61 and 62 are arranged in place of the bias power supplies V1 and V2 in FIG. 1 in correspondence with both the switches S1 and S2.
Hereinafter, the differences will be mainly described.

As shown in FIG. 16, the bias power supply voltage generation circuits 61 and 62 are connected to a Zener diode 71 and 72, which are elements whose voltage changes with temperature, and a constant voltage (for example, for example) across the Zener diode 71 and 72. It has power supplies B21 and B22 ( about several volts). The cathode side of the Zener diodes 71 and 72 is connected to the positive electrode terminal of the power supply B2 via resistors R31 and R32, and the anode side is connected to the negative electrode terminal of the power supplies B21 and B22. This makes it possible to automatically adjust the bias power supply voltage by utilizing the temperature dependence of the reverse voltage drop. Further, smoothing capacitors C21 and C22 are connected in parallel to the Zener diodes 71 and 72.

In FIG. 15, the bias power supply voltage generation circuits 61 and 62 are arranged between the diodes D1 and D2 and the source lines 11n and 12n. The anode side of the diodes D1 and D2 is connected to the connection points of the Zener diodes 71 and 72 and the resistors R31 and R32, respectively. In this way, the bias power supply voltage generation circuits 61 and 62 having the same configuration are provided on the switches S1 and S2 sides.

The Zener diodes 71 and 72 are connected in the opposite direction to the power supply V3, generate a Zener voltage Vz at both ends, and function as a bias power supply. Further, the Zener diodes 71 and 72 have a negative characteristic at a voltage of about several V or less, and the Zener voltage Vz decreases as the temperature rises. Utilizing this temperature characteristic, it is possible to generate a Zener voltage Vz that reflects the temperature on the switches S1 and S2 to which the source wires 11n and 12n are connected to the Zener diodes 71 and 72, and the bias power supply voltage can be changed. Can be made to.

Thereby, for each of the switches S1 and S2, the bias power supply voltage can be automatically adjusted according to the temperature of the switches S1 and S2. For example, when the temperature of the switch S1 is higher, the Zener voltage Vz becomes lower, and the charge charged to the capacitor C2 via the diode D1 decreases. Therefore, the added bias voltage is reduced as compared with the switch S2 side having a lower temperature, and the operation is performed in a direction in which the deviation of the switch timing becomes smaller. In this configuration, although the steady-state deviation remains, the temperature difference can be made smaller by repeating this operation.

By providing such bias power supply voltage generation circuits 61 and 62, it is possible to adjust the switch timing according to the temperature without separately providing the temperature detection circuit 4 and the control circuit 5. Further, since the Zener voltage Vz reflects the temperature characteristics such as the parasitic capacitance of the switches S1 and S2, the switch timing compensation can be performed with a relatively simple configuration.

Further, as shown in FIG. 17, instead of the Zener diodes 71 and 72 in FIG. 16, the diodes 81 and 82 can be used as the element whose voltage changes depending on the temperature. The anode side of the diodes 81 and 82 is connected to the positive electrode terminals of the power supplies B21 and B22 via resistors R31 and R32, and the cathode side is connected to the negative electrode terminals of the power supplies B21 and B22. Since the voltage drop that occurs between both ends of the diodes 81 and 82 also changes with temperature, it is possible to automatically adjust the bias power supply voltage by utilizing the temperature dependence of this forward voltage drop.

Alternatively, as shown in another modification shown in FIG. 18, instead of providing the diodes 81 and 82 in FIG. 17, a bias power supply voltage generation circuit in which the rectifying diodes D1 and D2 are also used as elements whose voltage changes depending on the temperature. 6 can also be arranged. In this case, the arrangement of the diodes D1 and D2 is the same as in the first and second embodiments, the anode side is connected to the positive electrode terminal of the power supply B22 provided in the bias power supply voltage generation circuit 6, and the cathode side is the negative electrode terminal of the power supply B22. Connected to. A smoothing capacitor Cb2 and a resistor Rb2 are connected in parallel to the power supply B22.

Although FIG. 18 shows the bias power supply voltage generation circuit 6 on the switch S2 side, the same can be applied to the switch S1 side. By doing so, the temperature detection circuit 4 and the control circuit 5 can be omitted, the number of parts can be further reduced, and the bias power supply voltage can be automatically adjusted.

(Embodiment 5)
The fifth embodiment according to the switching circuit will be described with reference to FIGS. 19 to 20.
As shown in FIG. 19, the basic configuration of the switching circuit 1 of this embodiment is the same as that of the fourth embodiment, for driving a plurality of switches S1 and S2 connected in parallel and a plurality of switches S1 and S2. It includes a drive circuit 2. Here, only the switch S2 side is shown, and the switch timing compensation circuit 3 is connected between the drive circuit 2 and the gate terminal of the switch S2. The switch timing compensation circuit 3 includes a bias capacitor C2 and a diode D2, and also includes a bias power supply voltage generation circuit 6 as a power supply voltage generator.

The bias power supply voltage generation circuit 6 includes a Seebeck element 9 as an element whose voltage changes depending on the temperature. The Seebeck element 9 is connected between the diode D2 and the source line 12n. The Seebeck element 9 is an element that generates an electromotive voltage according to a temperature difference between both ends, and has a function of serving as a temperature detection circuit 4 and a bias power supply by connecting both ends to switches S1 and S2. Further, a smoothing capacitor Cb2 and a discharge resistor Rb2 are connected in parallel to the Seebeck element 9. A similar bias power supply voltage generation circuit 6 can be provided on the switch S1 side as well.

As shown in FIG. 20, instead of connecting both ends of the Seebeck element 9 to the switches S1 and S2, one end is connected to the switch S2 and the other end is connected to a reference portion having a reference temperature, for example, a heat sink 91. You can also do it. On the switch S1 side, one end is connected to the switch S1 and the other end is connected to the heat sink 91 as a reference portion.

By providing such a bias power supply voltage generation circuit 6, it is possible to adjust the switch timing according to the temperature without separately providing the temperature detection circuit 4 and the control circuit 5.

The present invention is not limited to each of the above embodiments, and can be applied to various embodiments without departing from the gist thereof. For example, in the above embodiment, the discharge resistors R1 and R2 for discharging the bias capacitors C1 and C2 are arranged between the gate wires 11p and 12p and the source wires 12n and 12n, but the discharge resistors R1 and R2 are biased. It may be connected between both ends of the capacitors C1 and C2. Further, in the above embodiment, the switching circuit has been described as an example of application to an in-vehicle power conversion device, but the present invention is not limited to this, and the switching circuit can be applied to a device used for any purpose.

1 Switching circuit 2 Drive circuit 3 Switch timing compensation circuit 4 Temperature detection circuit (physical information detection circuit)
6 Bias power supply voltage generation circuit (power supply voltage generator)
C1, C2 Bias capacitor V1, V2 Variable bias (bias power supply)
S1, S2 switch D1, D2 diode

Claims (17)

A drive circuit (2) for driving a plurality of switches (S1, S2) connected in parallel, and
A switch timing compensation circuit (3) connected between the drive circuit and the gate terminals of one or more of the switches.
It is equipped with a temperature detection circuit (4) as a physical information detection circuit that detects temperature information as physical information that correlates with the switch characteristics of the above switch.
The switch timing compensation circuit includes bias capacitors (C1, C2) provided on gate wires (11p, 12p) connecting the gate terminal of the corresponding switch and the drive circuit, and a bias for charging the bias capacitor. A control circuit that controls the voltage of the bias power supply based on the power supply (V1, V2), the diodes (D1, D2) connected in series with the bias power supply, and the temperature information detected by the temperature detection circuit. Has (5, 51, 52) and
The diode has a configuration in which the cathode side is connected to the gate wire, the anode side is connected to the bias power supply, and the bias capacitor is charged via the diode.
The control circuit knows the voltage of the bias power supply from the comparison result by using the comparison result of the temperature information of the plurality of the switches or the comparison result of the temperature information of the corresponding switch and the reference temperature. A switching circuit that adjusts so that the difference in switch timing between a plurality of the above switches is small. Upper Symbol temperature detection circuit, as the temperature information, you detect the calorific value of the change of the switch due to the deviation of the switching characteristics, switching circuit of claim 1. The switching circuit according to claim 1 or 2, wherein in the switch timing compensation circuit , the control circuit adjusts the voltage of the bias power supply so as to reduce the temperature difference between the plurality of switches. The switching circuit according to any one of claims 1 to 3, wherein the switch timing compensation circuit has a configuration in which smoothing capacitors (Cb1 and Cb2) are connected in parallel with the bias power supply. The switching circuit according to claim 4, wherein the smoothing capacitor and the discharge resistor (Rb1, Rb2) connected in parallel are connected between the connection point of the diode and the bias power supply and the source terminal of the switch. The switching circuit according to any one of claims 1 to 5, wherein discharge resistors (R1 and R2) are connected in parallel between the bias capacitor and the gate terminal of the switch. The switching circuit according to any one of claims 1 to 6, wherein in the switch timing compensation circuit, the bias power supply is a plurality of variable biases provided corresponding to each of the plurality of switches. The switching circuit according to any one of claims 1 to 7, wherein the switch timing compensation circuit is connected to a part of the plurality of the switches. In the switching timing compensation circuit, the control circuit, by increasing and decreasing the voltage command value of the bias power source to a reference voltage which is set in advance, to control the voltage of the bias power supply connected to a part of the switch that switching circuit of claim 8. All of the plurality of the switches, Ri configuration der which the switching timing compensation circuit is connected, the switch timing compensation circuit, respectively connected to the plurality of the bias power corresponding to a plurality of said switches, a plurality of the switches The plurality of gate wires, the plurality of bias capacitors provided in the plurality of gate wires, and the plurality of diodes connected between the plurality of gate wires and the plurality of bias power supplies, respectively. that having a switching circuit according to any one of claims 1 to 7. In the switching timing compensation circuit, the control circuit, the difference between the values detected by the temperature detecting circuit to zero, a reference voltage which is set in advance, the part of the switch voltage of the bias power supply increases the command value for the other part of the switch, to reduce the voltage command value of the bias power supply, that controls the voltage of the bias power in which the switch is connected, according to claim 10 Switching circuit. In the switching timing compensation circuit, the control circuit, so that the difference of the values detected by the temperature detecting circuit is decreased, the reference voltage which is set in advance, the part of the switch voltage command of the bias power supply the value is a fixed value, for another part of the switch, to reduce the voltage command value of the bias power supply, that controls the voltage of the bias power in which the switch is connected, according to claim 10 Switching circuit. Each of the plurality of switches constitutes the upper arm switch of a half bridge circuit in which the source terminal of the upper arm switch and the drain terminal of the lower arm switch are connected. The switching circuit according to any one of claims 1 to 12, wherein one end is connected to the source terminal of the lower arm switch. To the switch timing compensation circuit, the temperature detection circuit for detecting the upper Stories temperature information, the bias power supply, and power supply voltage generating device functioning as the control circuit includes a (6), the supply voltage generator, temperature The switching circuit according to any one of claims 1 to 8 and 10 , which is configured by using an element whose voltage changes according to the above. In the power supply voltage generator, the element is a Zener diode (71, 72), and the Zener diode has a cathode side connected to a positive terminal of a constant voltage power supply (B21, B22) to cause a reverse voltage drop. the voltage of the bias power supply by utilizing the temperature dependency is set to automatic adjustable switching circuit of claim 14. In the power supply voltage generator, the element is the diode or another diode (81, 82), and the diode or the other diode is connected to the positive terminal of the power supply (B21, B22) having a constant voltage on the anode side. Te, the voltage of the bias power supply by utilizing the temperature dependency of the forward voltage drop is set to automatic adjustable switching circuit of claim 14. In the power supply voltage generator, the element is a Seebeck element (9), and both ends of the Seebeck element are connected to a plurality of the switches, or at a corresponding switch and a reference portion having a reference temperature. is connected, the voltage of the bias power supply by utilizing electromotive voltage generated by the temperature difference detected is set to automatic adjustable switching circuit of claim 14.

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