JP2022153040A - Control device and control method - Google Patents

Abstract

To suppress an overcurrent of a system mounting a DC-DC converter.SOLUTION: A control device 10 of a power supply system 100 comprises: a first isolating switch; a second isolating switch; a midpoint voltage detector that detects a midpoint voltage between a high-side switch element and a low-side switch element; a first voltage detector that measures a voltage between the first isolating switch and a converter; a second voltage detector that measures a voltage between a first power supply and the first isolating switch; a third voltage detector that measures a voltage between the second isolating switch and the converter; a fourth voltage detector that measures a voltage between a second power supply and the second isolating switch; a discharge circuit whose one end is electrically connected with a drain terminal of the high-side switch element and whose the other end is electrically connected with a source terminal of the low-side switch element; and a controller that turns off the first and second isolating switches after the midpoint voltage detector detects the midpoint voltage and confirms an operation of the converter.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a control device and control method.

As a power supply device for a vehicle, there is known a technology for supplying electric power based on a power storage unit at a lower voltage side than a predetermined position to a path on the low voltage side even when an abnormality occurs at a higher voltage side than the predetermined position of the power supply device. (see Patent Document 1).

JP 2018-148733 A

A non-insulated DC-DC converter is installed in a system such as a vehicle with two power sources such as batteries or storage batteries connected to each other. If the main switch section of the DC-DC converter is out of order, overcurrent may occur even before operation, blowing the fuse.

An object of the present disclosure is to provide a control device and a control method capable of suppressing overcurrent in a system equipped with a DC-DC converter in advance or before operation of the DC-DC converter.

A control device according to the present disclosure includes a high-side switch element provided between a first power supply and a second power supply, a drain terminal of which is electrically connected to a power supply line, and a drain terminal of the high-side switch element. a converter including at least one low-side switch element electrically connected to a source terminal and the source terminal electrically connected to a ground line; one end of which is electrically connected to the positive electrode of the first power supply; a first cut-off switch part having the other end electrically connected to the drain of the high side switch element; one end electrically connected to the positive electrode of the second power supply and the other end connected to the drain of the high side switch element; a second cut-off switch section electrically connected; a midpoint voltage detection section for detecting a midpoint voltage between the high-side switch element and the low-side switch element; the first cut-off switch section and the converter; a first voltage detection unit that measures the voltage between the first power supply and the first cutoff switch unit; a second voltage detection unit that measures the voltage between the first cutoff switch unit; and the second cutoff switch unit and the converter a third voltage detection unit that measures the voltage between the second power supply and the second cutoff switch unit; a fourth voltage detection unit that measures the voltage between the second power supply and the second cutoff switch unit; a discharge circuit unit electrically connected to the terminal and having the other end electrically connected to the source terminal of the low-side switch element; a control unit configured to turn off the first cutoff switch unit and the second cutoff switch unit, wherein the control unit controls the detection result of the first voltage detection unit and the detection result of the third voltage detection unit; Based on the detection result of the measured value, the discharge circuit section is controlled to discharge the charge accumulated inside the converter.

In the control device of the present disclosure, the control unit controls the discharge circuit unit when the detection result of the first voltage detection unit and the detection result of the third voltage detection unit are equal to or greater than a predetermined threshold value. , to discharge the charge accumulated inside the converter.

In the control device of the present disclosure, the threshold of the detection result of the first voltage detection unit is set based on the detection result of the second voltage detection unit, and the threshold of the detection result of the third voltage detection unit is set to the fourth voltage. It is set based on the detection result of the detection unit.

A control method according to the present disclosure includes a high-side switch element provided between a first power supply and a second power supply, a drain terminal of which is electrically connected to a power supply line, and a drain terminal of the high-side switch element. a low side switch element electrically connected to a source terminal and a source terminal electrically connected to a ground line; one end is electrically connected to the positive electrode of the first power supply and the other end is electrically connected to the drain of the high-side switch element after detecting the midpoint voltage and confirming the operation of the converter after detecting the midpoint voltage and confirming the operation of the converter; and a second cut-off switch unit having one end electrically connected to the positive electrode of the second power supply and the other end electrically connected to the drain of the high-side switch element. controlling to an off state; measuring a voltage between the first cut-off switch section and the converter; measuring a voltage between the first power supply and the first cut-off switch section; measuring a voltage between the second cut-off switch section and the converter; measuring a voltage between the second power supply and the second cut-off switch section; and measuring a voltage between the first cut-off switch section and the converter. and discharging electric charges accumulated inside the converter based on a detection result of a voltage between the converter and a detection result of the voltage between the second cutoff switch section and the converter.

According to the present disclosure, overcurrent in a system equipped with a DC-DC converter can be suppressed in advance or before operation of the DC-DC converter.

FIG. 1 is a diagram showing a configuration example of a power supply system according to the first embodiment. FIG. 2 is a diagram showing a configuration example of a cutoff switch section. FIG. 3 is a diagram showing a configuration example of a modification of the cut-off switch section. FIG. 4 is a diagram showing a configuration example of a modification of the cut-off switch section. FIG. 5 is a diagram showing a configuration example of a modification of the cut-off switch section. FIG. 6 is a diagram for explaining a method of detecting a midpoint voltage between a switching element on the high side and a switching element on the low side. FIG. 7 is a timing chart for explaining a switching element failure determination process according to the first embodiment. FIG. 8 is a flowchart showing an example of the flow of failure determination processing of the cut-off switch section according to the first embodiment. FIG. 9 is a flow chart showing an example of the flow of failure judgment processing of the switching element of the engagement/disengagement switch section according to the first embodiment. FIG. 10 is a diagram illustrating a configuration example of a power supply system according to the second embodiment. FIG. 11 is a timing chart for explaining discharge processing according to the second embodiment. FIG. 12 is a flowchart showing an example of the flow of discharge processing of the converter according to the second embodiment.

Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the present disclosure is not limited by this embodiment, and in the following embodiments, the same parts are given the same reference numerals to omit redundant description.

[First embodiment]
FIG. 1 is a diagram showing a configuration example of a power supply system according to the first embodiment. A power supply system 100 includes a first power supply 1 , a second power supply 2 , a fuse 3 , a fuse 4 , and a control device 10 .

The first power supply 1 is a power supply device that supplies power to the control device 10 . The voltage of the first power supply 1 is, for example, 24V or 48V, but is not limited to this. The first power supply 1 outputs voltage to a power source such as a motor (not shown).

The second power supply 2 is a power supply device that supplies power to the control device 10 . The second power supply 2 is a power supply device that outputs a voltage lower than that of the first power supply 1 . The voltage of the second power supply 2 is, for example, 12V, but is not limited to this. The second power supply 2 may be, for example, a capacitor. The second power supply 2 outputs voltage to onboard equipment such as a wiper.

The fuse 3 has one end electrically connected to the positive electrode of the first power supply 1 and the other end electrically connected to the current detector 11 of the control device 10 . A fuse 3 is provided to protect the first power supply 1 . The fuse 3 is a current fuse that melts due to self-heating when the passing current exceeds the rated current. The fuse 3 blows when excessive current exceeding the rated current flows from the control device 10 to prevent excessive current from flowing into the first power source 1 and various devices connected to the first power source 1.

The fuse 4 has one end electrically connected to the positive electrode of the second power supply 2 and the other end electrically connected to the current detector 17 of the control device 10 . A fuse 4 is provided to protect the second power supply 2 . The fuse 4 is a current fuse that melts due to self-heating when the passing current exceeds the rated current. The fuse 4 blows when excessive current exceeding the rated current flows from the control device 10 to prevent excessive current from flowing into the second power supply 2 .

The control device 10 includes a current detection unit 11, a cutoff switch unit 12, an overcurrent detection unit 13, a voltage detection unit 14, a voltage detection unit 15, an output capacitor 16, a current detection unit 17, and a cutoff switch unit 18. , an overcurrent detection unit 19, a voltage detection unit 20, a voltage detection unit 21, an output capacitor 22, a converter 23, a switching element diagnosis unit 24, a midpoint voltage detection unit 25, a control unit 26, Prepare.

The current detection section 11 has one end electrically connected to the fuse 3 and the other end electrically connected to the cutoff switch section 12 . Current detection unit 11 detects an output current output from converter 23 . The current detection section 11 outputs a current detection signal corresponding to the detection result to the overcurrent detection section 13 . The current detection unit 11 is, for example, a known current sensor, but is not limited to this.

The cut-off switch section 12 has one end electrically connected to the current detection section 11 and the other end connected to the converter 23 . The cutoff switch section 12 is configured to cut off electrical connection between the first power supply 1 and the converter 23 . The cut-off switch section 12 is also called a first cut-off switch section.

FIG. 2 is a diagram showing a configuration example of a cutoff switch section. In FIG. 2, the fuse 3 and the current detector 11 are omitted. As shown in FIG. 2, the cut-off switch section 12 includes a switching element Q11. The switching element Q11 is a transistor such as a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). That is, the cut-off switch section 12 is composed of a semiconductor element. Switching element Q11 electrically disconnects between first power supply 1 and converter 23 when in the OFF state. Switching element Q<b>11 switches to an ON state when a control signal is input to its gate, and electrically connects first power supply 1 and converter 23 . The switching element Q11 may be a silicon power device, a GaN power device, a SiC power device, an IGBT (Insulated Gate Bipolar Transistor), or the like.

Note that the configuration of the cut-off switch section 12 is not limited to the configuration example shown in FIG. 3, 4, and 5 are diagrams showing configuration examples of modifications of the cut-off switch section.

As shown in FIG. 3, the cut-off switch section 12A may include a switching element Q11 and a switching element Q12. The switching element Q11 has, for example, a drain terminal electrically connected to the first power supply 1 and a source terminal electrically connected to the source terminal of the switching element Q12. The switching element Q12 may have, for example, a source terminal electrically connected to the source terminal of the switching element Q11 and a drain terminal electrically connected to the converter 23 . In the example shown in FIG. 3, a common control signal is input to each of the gate terminal of the switching element Q11 and the gate terminal of the switching element Q12.

As shown in FIG. 4, the cut-off switch section 12B may include a switching element Q11 and a switching element Q12. The cut-off switch section 12B differs from the cut-off switch section 12A shown in FIG. 3 in that different control signals are input to the source terminal of the switching element Q11 and the gate terminal of the switching element Q12. different.

As shown in FIG. 5, the cutoff switch section 12C may include a relay RY. The cut-off switch section 12C may be configured mechanically. In this case, the relay RY electrically disconnects or electrically connects the first power supply 1 and the converter 23 by mechanical operation.

Return to FIG. The overcurrent detector 13 detects overcurrent based on the current detection signal received from the current detector 11 . The overcurrent detection unit 13 detects overcurrent according to, for example, an overcurrent diagnostic signal from the control unit 26 . For example, when detecting an overcurrent, the overcurrent detection unit 13 outputs a control signal to the overcurrent stop circuit unit 32 .

Voltage detection unit 14 detects the voltage between cutoff switch unit 12 and converter 23 . Voltage detection unit 14 outputs the detection result of the voltage between cutoff switch unit 12 and converter 23 to control unit 26 . The voltage detection section 14 is also called a first voltage detection section.

Voltage detector 15 detects the voltage between fuse 3 and current detector 11 . The voltage detection section 15 outputs the detection result of the voltage between the fuse 3 and the current detection section 11 to the control section 26 . The voltage detection section 15 is also called a second voltage detection section.

Output capacitor 16 smoothes the voltage from converter 23 . The voltage of the output capacitor 16 becomes the voltage output to the first power supply 1 side.

The current detection section 17 has one end electrically connected to the fuse 4 and the other end electrically connected to the cutoff switch section 18 . Current detector 17 detects an output current output from converter 23 . The current detector 17 outputs a current detection signal corresponding to the detection result to the overcurrent detector 19 . The current detector 17 is, for example, a known current sensor, but is not limited to this.

The cut-off switch section 18 has one end electrically connected to the current detection section 17 and the other end connected to the converter 23 . The cutoff switch section 18 is configured to cut off electrical connection between the second power supply 2 and the converter 23 . The cut-off switch section 18 can be configured in the same manner as the cut-off switch section 12 shown in FIGS. The cut-off switch section 18 is also called a second cut-off switch section.

The overcurrent detector 19 detects overcurrent based on the current detection signal received from the current detector 17 . The overcurrent detection unit 19 detects overcurrent according to, for example, an overcurrent diagnostic signal from the control unit 26 . For example, when detecting an overcurrent, the overcurrent detection unit 19 outputs a control signal to the overcurrent stop circuit unit 32 .

Voltage detection unit 20 detects the voltage between cutoff switch unit 18 and converter 23 . Voltage detection unit 20 outputs the detection result of the voltage between cutoff switch unit 18 and converter 23 to control unit 26 . The voltage detection section 20 is also called a third voltage detection section.

Voltage detector 21 detects the voltage between fuse 4 and current detector 17 . Voltage detection unit 21 outputs the detection result of the voltage between fuse 4 and current detection unit 17 to control unit 26 . Voltage detector 21 is also called a fourth voltage detector.

Output capacitor 22 smoothes the voltage from converter 23 . The voltage of the output capacitor 22 becomes the voltage output to the second power supply 2 side.

The converter 23 is a bidirectional DC-DC converter. The converter 23 includes a switching element Q1, a switching element Q3, . . . , a switching element Qp (p is an arbitrary odd number) on the high side. The converter 23 includes a switching element Q2, a switching element Q4, . . . , a switching element Qn (n is any even number) on the low side. The converter 23 has the same number of switching elements on the high side and the low side. The converter 23 may include at least a high-side switching element Q1 and a low-side switching element Q2.

The high-side switching element Q1, the switching element Q3, . The high-side switching element Q1, the switching element Q3, . The switching element Q1 on the high side, the switching element Q3, . electrically connected to the terminal.

The source terminals of the switching elements Q2, Q4, . . . , Qn on the low side are electrically connected to a low potential (ground line).

The converter 23 includes a capacitor C1, a capacitor C2, . . . a capacitor Cm (m is an arbitrary integer).

The capacitor C1 has one end electrically connected to the drain terminal of the switching element Q1 and the other end electrically connected to the source terminal of the switching element Q2. The capacitor C2 has one end electrically connected to the drain terminal of the switching element Q3 and the other end electrically connected to the source terminal of the switching element Q4. The capacitor Cm has one end electrically connected to the drain terminal of the switching element Qp and the other end electrically connected to the source terminal of the switching element Qn. That is, in the converter 23, capacitors are connected in parallel to the switching element on the high side and the switching element on the low side. Capacitors C1 to Cm suppress noise generated when each switching element performs a switching operation.

The converter 23 includes a coil L1, a coil L2, . . . , and a coil Lm.

The coil L<b>1 has one end electrically connected between the switching element Q<b>1 and the switching element Q<b>2 and the other end electrically connected to the cut-off switch section 18 . The coil L2 has one end electrically connected between the switching element Q3 and the switching element Q4 and the other end electrically connected to the cutoff switch section 18 . The coil Lm has one end electrically connected between the switching element Qp and the switching element Qn, and the other end electrically connected to the cut-off switch section 18 . That is, in the converter 23 , coils are electrically connected between the switch elements on the high side and the switch elements on the low side and between the cutoff switch section 18 . In other words, each coil has one end electrically connected between the switch element on the high side and the switch element on the low side, and the other end electrically connected to the cutoff switch section 18 . That is, in the converter 23, the cut-off switch section 18 is electrically connected between each switching element on the high side and each switching element on the low side.

Switching element diagnosis unit 24 outputs a signal for determining failure of each switch element of converter 23 . The switching element diagnostic unit 24 outputs, for example, a voltage Vc from an auxiliary power supply different from the first power supply 1 and the second power supply 2 as a signal for determining failure of each switch element of the converter 23 . The auxiliary power supply is, for example, a power supply (not shown) that generates necessary power inside the converter 23 .

The midpoint voltage detection unit 25 detects a midpoint voltage, which is a voltage between each switch element on the high side and each switch element on the low side. The midpoint voltage detection unit 25 detects, for example, the midpoint voltage between the switching element Q1 and the switching element Q2.

The control unit 26 includes a cut-off switch drive unit 30, a cut-off switch drive unit 31, an overcurrent stop circuit unit 32, a switching element control unit 33, and a power supply control unit .

The cut-off switch driving section 30 switches the cut-off switch section 12 between an ON state and an OFF state. For example, when measuring the midpoint voltage between the high-side switching element and the low-side switching element of the converter 23 , the isolation switch driving section 30 turns off the isolation switch section 12 .

The cut-off switch driving section 31 switches the cut-off switch section 18 between an ON state and an OFF state. For example, when measuring the midpoint voltage between the high-side switching element and the low-side switching element of the converter 23 , the isolation switch driving section 31 turns off the isolation switch section 18 .

Overcurrent stop circuit unit 32 outputs a control signal for stopping each switching element of converter 23 when overcurrent detection unit 13 or overcurrent detection unit 19 detects an overcurrent.

Switching element control unit 33 controls each switching element of converter 23 . For example, when the overcurrent detection unit 13 or the overcurrent detection unit 19 detects an overcurrent, the switching element control unit 33 controls each switching element of the converter 23 according to the control signal from the overcurrent stop circuit unit 32. do. Switching element control unit 33 switches the target switching element to an off state in order to determine a short-circuit fault in the target switching element of converter 23 . Switching element control unit 33 switches the target switching element to the ON state in order to determine an open failure of the target switching element of converter 23 .

The power control unit 34 controls each unit of the control device 10 . For example, the power control unit 34 outputs a control signal S1 to the overcurrent detection unit 13 to detect overcurrent. For example, the power control unit 34 outputs a control signal S2 to the overcurrent detection unit 19 to detect overcurrent. The power control unit 34 outputs, for example, a control signal S3 to the cut-off switch drive unit 30 to control the cut-off switch unit 12 . The power control unit 34 outputs, for example, a control signal S4 to the cut-off switch driving unit 31 to control the cut-off switch unit 18 . For example, the power control unit 34 outputs a control signal S5 to the switching element diagnosis unit 24, and executes processing for detecting a midpoint voltage between the high-side switching element and the low-side switching element of the converter 23. Let The power control unit 34 outputs, for example, a control signal S6 to the switching element control unit 33 to control each switching element.

The power control unit 34 acquires the detection result of the voltage between the cutoff switch unit 12 and the converter 23 from the voltage detection unit 14 . The power control unit 34 acquires the detection result of the voltage between the fuse 3 and the current detection unit 11 from the voltage detection unit 15 . The power control unit 34 acquires the detection result of the voltage between the cutoff switch unit 18 and the converter 23 from the voltage detection unit 20 . The power control unit 34 acquires the detection result of the voltage between the fuse 4 and the current detection unit 17 from the voltage detection unit 21 . The power control unit 34 determines a short-circuit failure of the cutoff switch unit 12 and the cutoff switch unit 18 based on the detection results obtained from the voltage detection unit 14, the voltage detection unit 15, the voltage detection unit 20, and the voltage detection unit 21. do.

The power control unit 34 acquires the detection result of the intermediate voltage between the switching element on the high side and the low side of the converter 23 from the midpoint voltage detection unit 25 . Based on the detection result of the midpoint voltage obtained from the midpoint voltage detection unit 25, the power supply control unit 34 determines short-circuit failure and open failure of the switching element on the high side and the switching element on the low side.

A method of detecting the midpoint voltage between the switching element on the high side and the switching element on the low side will be described with reference to FIG. A method for detecting the midpoint voltage between the switching element Q1 and the switching element Q2 will be described below.

As shown in FIG. 6, the switching element diagnosis unit 24 includes a transistor Tr1, a diode 241, and a resistance element 242.

The transistor Tr1 is, for example, a bipolar transistor, but is not limited to this. A voltage Vc from an auxiliary power supply (not shown) is input to the emitter terminal of the transistor Tr1. A control signal S5 from the power control unit 34 is input to the base terminal of the transistor Tr1. By inputting the control signal S5 to the base terminal of the transistor Tr1, a current corresponding to the voltage Vc input to the emitter terminal flows from the emitter terminal to the collector terminal.

The diode 241 has an anode terminal electrically connected to the collector terminal of the transistor Tr1 and a cathode terminal electrically connected to one end of the resistance element 242 .

The resistance element 242 has one end electrically connected to the cathode terminal of the diode 241 and the other end electrically connected to the drain terminal of the switching element Q1. The resistive element 242 is a resistive element for current limitation.

That is, the switching element diagnosis unit 24 applies the voltage Vc to the drain terminal of the switching element Q1 by inputting the voltage Vc to the emitter terminal of the transistor Tr1 and inputting the control signal S5 to the base terminal thereof.

The midpoint voltage detection section 25 includes a Zener diode 251 , a resistance element 252 , a voltage dividing circuit 253 and a voltage detection section 254 .

The Zener diode 251 has an anode terminal electrically connected to the source terminal of the switching element Q2 and a cathode terminal electrically connected to one end of the resistance element 252 .

The resistance element 252 has one end electrically connected to the cathode terminal of the Zener diode 251 and the other end electrically connected to the other end of the coil L1 having one end electrically connected between the switching element Q1 and the switching element Q2. It is connected to the.

The voltage dividing circuit 253 has one end electrically connected to the cathode terminal of the Zener diode 251 and the other end electrically connected to the anode terminal of the Zener diode 251 . In other words, the voltage divider circuit 253 is connected in parallel with the Zener diode 251 .

The voltage detection unit 254 detects the midpoint voltage between the switching element Q1 and the switching element Q2 from the output from the voltage dividing circuit 253. FIG.

The switching element control unit 33 switches the switching element Q1 between the ON state and the OFF state when detecting the midpoint voltage between the switching element Q1 and the switching element Q2. By detecting the midpoint voltage between the switching element Q1 and the switching element Q2, it is possible to determine the failure of the switching element Q1 or the switching element Q2.

For example, when the switching element Q1 is in the OFF state, the midpoint voltage between the switching element Q1 and the switching element Q2 is 0 if the switching element Q1 is normal. When the switching element Q1 has a short-circuit failure, the midpoint voltage between the switching element Q1 and the switching element Q2 is the voltage Vc of the auxiliary power supply input to the switching element diagnosis section 24 .

For example, when the switching element Q1 is in the ON state, if the switching element Q1 is normal, the midpoint voltage between the switching element Q1 and the switching element Q2 is the voltage Vc of the auxiliary power supply input to the switching element diagnosis unit 24. . When switching element Q1 has an open failure, the midpoint voltage between switching element Q1 and switching element Q2 is zero. When the switching element Q2 has a short-circuit failure, the midpoint voltage between the switching element Q1 and the switching element Q2 gradually changes from the voltage Vc of the auxiliary power supply input to the switching element diagnosis section 24 to 0. do.

That is, the failure of switching element Q1 or switching element Q2 can be determined based on the state of switching element Q1 and the value of the midpoint voltage between switching element Q1 and switching element Q2.

A switching element failure determination process according to the first embodiment will be described with reference to FIG. 7 . FIG. 7 is a timing chart for explaining a switching element failure determination process according to the first embodiment. The timing chart shown in FIG. 7 is a timing chart when the cutoff switch section 12 has the configuration shown in FIG. 2 and the cutoff switch section 18 has the configuration shown in FIG.

FIG. 7 shows a process of determining failure of switching element Q1 or switching element Q2 of converter 23 according to the first embodiment.

In FIG. 7, the period from timing t1 to timing t2 is the confirmation period for the short-circuit failure of the cut-off switch section 12 and the cut-off switch section 18 . A period from timing t2 to timing t5 is a confirmation period of the midpoint voltage between the switching element Q1 and the switching element Q2.

In FIG. 7, (a) shows the voltage value of the auxiliary power supply that supplies voltage to the switching element diagnosis section 24. In FIG. (b) shows the state of the cut-off switch section 12. FIG. (c) shows the state of the cut-off switch section 18 . (d) shows the state of the switching element Q1. (e) shows the state of the switching element Q2. (f) shows the state of the switching element diagnostic unit 24; (g) shows the voltage value of the midpoint voltage between the switching element Q1 and the switching element Q2. In (h), a waveform 101 indicates the voltage detection result of the voltage detection unit 14 and a waveform 102 indicates the voltage detection result of the voltage detection unit 15 . In (i), a waveform 201 indicates the voltage detection result of the voltage detection unit 20 and a waveform 202 indicates the voltage detection result of the voltage detection unit 21 .

The voltage value of the auxiliary power supply is Vc during the period from timing t1 to timing t5. The cut-off switch section 12, the cut-off switch section 18, and the switching element Q2 are in the OFF state during the period from timing t1 to timing t5. The voltage value detected by the voltage detection unit 15 during the period from timing t1 to timing t5 is V1, which is the voltage value of the first power supply 1 . The voltage value detected by the voltage detection unit 21 during the period from timing t1 to timing t5 is V2, which is the voltage value of the second power supply 2 .

At timing t1, the switching element diagnosis unit 24 receives the control signal S5 and switches to the ON state. As a result, the voltage value of Vc is applied to the drain terminal of the switching element Q1 at the timing t1. At timing t1, as indicated by waveform 101, the voltage value detected by voltage detector 14 gradually increases.

At timing t2, as indicated by waveform 101, the voltage value detected by voltage detection unit 14 reaches V1a. In the period from timing t2 to timing t3, if there is no failure in the cutoff switch section 12 and the cutoff switch section 18, the detection result of the voltage detection section 14 is V1a, the detection result of the voltage detection section 15 is V1, and the detection result of the voltage detection section 20 is V1a. The result is 0, and the detection result of the voltage detection unit 21 is V2.

During the period from timing t3 to timing t4, the switching element Q1 is in the OFF state, and the midpoint voltage between the switching elements Q1 and Q2 is zero. In the period from timing t3 to timing t4, if a short-circuit fault occurs in the switching element Q1, the value of the midpoint voltage becomes Vc.

At timing t4, the switching element Q1 is turned on. When switching element Q1 is turned on, the midpoint voltage between switching element Q1 and switching element Q2 gradually increases.

During the period from timing t4 to timing t5, the midpoint voltage between switching element Q1 and switching element Q2 reaches divided voltage Vc1 obtained by dividing Vc of the auxiliary power supply according to voltage dividing circuit 253 . During the period from timing t4 to timing t5, when the switching element Q1 has an open failure, the midpoint voltage between the switching element Q1 and the switching element Q2 becomes zero. In the period from timing t4 to timing t5, when the switching element Q2 has a short-circuit failure, the midpoint voltage between the switching elements Q1 and Q2 reaches Vc and then gradually changes to 0. During the period from timing t4 to timing t5, the detection result of the voltage detection unit 20 reaches V2a, which is a predetermined voltage value.

At timing t5, the switching element Q1 is turned off.

During the period from timing t5 to timing t6, the midpoint voltage between switching element Q1 and switching element Q2 becomes zero. The detection result of the voltage detection unit 20 becomes 0 during the period from timing t5 to timing t6.

At timing t6, the switching element diagnosis unit 24 is turned off. Thus, the switching element failure determination process according to the first embodiment ends.

[Processing content]
Processing contents of the control unit according to the first embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing an example of the flow of failure determination processing of the cut-off switch section according to the first embodiment.

The processing of the control unit 26 shown in FIG. 8 is performed with the cutoff switch unit 12 and the cutoff switch unit 18 turned off.

The control unit 26 determines whether or not the voltage inside the cutoff switch unit 18 on the side of the second power supply 2 is less than a predetermined value (step S101). Specifically, the control unit 26 determines whether the voltage detection result of the voltage detection unit 20 is less than a predetermined value. If it is determined that the voltage inside the cutoff switch section 18 is less than the predetermined value (step S101; Yes), the process proceeds to step S102. If it is not determined that the voltage inside the cutoff switch section 18 is less than the predetermined value (step S101; No), the process proceeds to step S104.

If it is determined Yes in step S101, it is determined whether or not the voltage inside the cutoff switch section 12 on the side of the first power supply 1 is less than a predetermined value (step S102). In particular. The control unit 26 determines whether the voltage detection result of the voltage detection unit 14 is less than a predetermined value. If it is determined that the voltage inside the cutoff switch section 12 is less than the predetermined value (step S102; Yes), the process proceeds to step S103. If it is not determined that the voltage inside the cutoff switch section 12 is less than the predetermined value (step S102; No), the process proceeds to step S104.

When it is determined as Yes in step S102, the control section 26 determines that the cut-off switch section 12 and the cut-off switch section 18 are normal (step S103). Specifically, the control unit 26 determines that the disconnection switch unit 12 and the disconnection switch unit 18 are not out of order. Then, the processing of FIG. 8 ends.

When it is determined as No in step S101 or step S102, the control section 26 determines that the cut-off switch section 12 or the cut-off switch section 18 is abnormal (step S104). Specifically, when it is determined No in step S101, the control unit 26 determines that the cut-off switch unit 18 is out of order. If the control unit 26 determines No in step S102, it determines that the cut-off switch unit 12 is out of order. When the control unit 26 determines that the cut-off switch unit 12 or the cut-off switch unit 18 is out of order, it outputs information to that effect to a host device (not shown). Then, the processing of FIG. 8 ends.

Processing contents of the control unit according to the first embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing an example of the flow of failure determination processing for switching elements of the cut-off switch unit according to the first embodiment. In the following, an example of determining failure of the switching element Q1 and the switching element Q2 will be described.

The processing of the control unit 26 shown in FIG. 9 is performed with the cutoff switch unit 12 and the cutoff switch unit 18 in the OFF state.

The control unit 26 turns on the switching element diagnosis unit 24 (step S201). Specifically, the control section 26 outputs the control signal S5 to the switching element diagnosis section 24 to turn on the switching element diagnosis section 24 . Then, the process proceeds to step S202.

The control unit 26 determines whether voltage is detected inside the cutoff switch unit 12 on the side of the first power supply 1 (step S202). Specifically, the control unit 26 determines whether or not the voltage detection unit 20 has detected the voltage. If it is determined that the voltage is detected inside the cutoff switch section 12 (step S202; Yes), the process proceeds to step S203. If it is not determined that the voltage is detected inside the cut-off switch section 12 (step S202; No), the process proceeds to step S210.

When determined as Yes in step S202, the control unit 26 determines whether or not the midpoint voltage is 0 (step S203). Specifically, the control unit 26 determines whether or not the midpoint voltage between the switching element Q1 and the switching element Q2 detected by the midpoint voltage detection unit 25 is zero. If it is determined that the midpoint voltage is 0 (step S203; Yes), the process proceeds to step S204. If it is determined that the midpoint voltage is not 0 (step S203; No), the process proceeds to step S210.

If determined as Yes in step S203, the control unit 26 switches the switching element Q1 to the ON state (step S204). Then, go to step 205 .

The control unit 26 determines whether or not the midpoint voltage is a predetermined value (step S205). Specifically, the control unit 26 determines whether or not the midpoint voltage between the switching element Q1 and the switching element Q2 detected by the midpoint voltage detection unit 25 is the voltage Vc of the auxiliary power supply. If it is determined that the midpoint voltage is the predetermined value (step S205; Yes), the process proceeds to step S206. If the midpoint voltage is not determined to be the predetermined value (step S205; No), the process proceeds to step S210.

The control unit 26 determines whether or not the voltage inside the cutoff switch unit 18 on the side of the second power supply 2 is equal to or higher than a predetermined value (step S206). Specifically, the control unit 26 determines whether the voltage detected by the voltage detection unit 20 is equal to or higher than a predetermined value. If it is determined that the voltage inside the cutoff switch unit 18 is equal to or higher than the predetermined value (step S206; Yes), the process proceeds to step S207. If it is not determined that the voltage inside the cutoff switch unit 18 is equal to or higher than the predetermined value (step S206; No), the process proceeds to step S210.

When it is determined as Yes in step S206, the control unit 26 determines that it is normal (step S207). Specifically, the control unit 26 determines that the switching element Q1, the switching element Q2, and the coil L1 are not out of order. Then, the process proceeds to step S208.

The control unit 26 switches the switching element Q1 to the OFF state (step S208). Then, the process proceeds to step S209.

The control unit 26 turns off the switching element diagnosis unit 24 (step S209). Specifically, the control unit 26 stops the control signal S5 to turn off the switching element diagnosis unit 24 . Then, the processing of FIG. 9 ends.

If it is determined No in step S202, No in step S203, No in step S205, or No in step S206, the control unit 26 determines that there is an abnormality (step S210). Specifically, when the determination in step S202 is No, the control unit 26 determines that the auxiliary power supply is abnormal. If the determination in step S203 is No, the control unit 26 determines that the switching element Q1 has a short-circuit failure. If it is determined No in step S205 and the detected voltage is 0, the control unit 26 determines that Q1 has an open failure. When the determination in step S205 is No, the control unit 26 determines that the switching element Q2 has a short-circuit failure when the detected voltage changes from the voltage Vc of the auxiliary power supply to 0. If the determination in step S<b>206 is No, the control unit 26 determines that the precharge abnormality is caused by the second power supply 2 . If the determination in step S206 is No, the control unit 26 determines that the failure is caused by the coil L1. An example of failure caused by the coil L1 will be described. For example, in step S206, since the switching element Q1 and the switching element diagnosis section 24 are in the ON state, the voltage Vc of the auxiliary power supply is applied to the cutoff switch section 18 from the coil L1. Here, the abnormality of the voltage from the auxiliary power supply is determined in step S202. Therefore, for example, when the coil L1 has an open failure, the control unit 26 determines No in step S206. Then, the processing of FIG. 9 ends.

As described above, in the first embodiment, while two power supplies are connected to the converter 23, by measuring the midpoint voltage of the switching element on the high side and the switching element on the low side of the converter 23, each switching element failure determination can be performed. As a result, in the first embodiment, even if a failure occurs in each switching element, failure determination of each switching element can be performed without blowing the fuse provided between the converter 23 and the power supply. It can be carried out.

[Second embodiment]
FIG. 10 is a diagram illustrating a configuration example of a power supply system according to the second embodiment. The power supply system 100A is different from the power supply system 100 shown in FIG. 1 in that the discharge circuit section 27 and the control section 26A are provided with the discharge circuit driving section 35 .

After the converter 23 starts to operate, when the operation ends, electric charges may remain in the capacitors C1 to Cm inside the converter 23 . When performing the process of detecting the midpoint voltage before the next operation of the converter 23, if the charge remains inside the converter 23, the reference value changes, so an accurate midpoint voltage value is detected. may not be possible. Therefore, in the second embodiment, the charge inside the converter 23 is discharged after the operation of the converter 23 is finished.

The discharge circuit unit 27 has one end electrically connected to the drain terminal of the high-side switching element of the converter 23 and the other end electrically connected to the source terminal of the low-side switching element of the converter 23 . Discharge circuit unit 27 discharges electric charges inside converter 23 in accordance with a control signal from discharge circuit drive unit 35 . Discharging circuit unit 27 discharges electric charges inside converter 23 when cutoff switch unit 12 and cutoff switch unit 18 are in the OFF state. The discharge circuit section 27 is composed of, for example, a transistor, but is not limited to this.

The discharge circuit drive unit 35 outputs a control signal to the discharge circuit unit 27 to drive the discharge circuit unit 27 and discharge the electric charge inside the converter 23 . The discharge circuit drive section 35 outputs a control signal to the discharge circuit section 27 under the control of the power supply control section 34 .

The power control unit 34 outputs a control signal to the discharge circuit drive unit 35 to cause the discharge circuit drive unit 35 to drive the discharge circuit unit 27 . For example, when the voltage detection results of the voltage detection unit 14 and the voltage detection unit 20 become equal to or less than a predetermined voltage value, the power supply control unit 34 stops outputting the control signal.

The discharging process of the converter according to the second embodiment will be described with reference to FIG. 11 . FIG. 11 is a timing chart for explaining discharge processing according to the second embodiment. The timing chart shown in FIG. 11 is a timing chart when the cutoff switch section 12 has the configuration shown in FIG. 2 and the cutoff switch section 18 has the configuration shown in FIG.

FIG. 11 shows the processing after the converter 23 finishes its operation. In FIG. 11, the period from timing t3 to timing t4 is the period during which the charge inside the converter 23 is discharged.

In FIG. 11 , (a) shows the voltage value of the auxiliary power supply that supplies voltage to the switching element diagnostic section 24 . (b) shows the state of the cut-off switch section 12. FIG. (c) shows the state of the cut-off switch section 18 . (d) shows the state of the switching element Q1. (e) shows the state of the switching element Q2. (f) shows the state of the switching element diagnostic unit 24; (g) shows the voltage value of the midpoint voltage between the switching element Q1 and the switching element Q2. In (h), a waveform 101 indicates the voltage detection result of the voltage detection unit 14 and a waveform 102 indicates the voltage detection result of the voltage detection unit 15 . In (i), a waveform 201 indicates the voltage detection result of the voltage detection unit 20 and a waveform 202 indicates the voltage detection result of the voltage detection unit 21 . (j) indicates the state of the discharge circuit section 27 .

At timing t1, each switching element is turned off, and the cut-off switch section 12 is turned off. During the period from timing t1 to timing t2, the voltage value detected by the voltage detection section 20 decreases.

At timing t2, the cut-off switch section 18 is turned off.

At timing t3, the discharge circuit section 27 is turned on. During the period from timing t3 to timing t4, the discharge circuit section 27 remains on.

During the period from timing t3 to timing t4, the voltage value detected by the voltage detection unit 14 decreases. At timing t4, the discharge circuit section 27 is turned off.

During the period from timing t4 to timing t5, the auxiliary power supply is turned off due to a command from a host device (not shown) or a stop command from an external device. This completes the discharge process according to the second embodiment.

[Processing content]
Processing contents of the control unit according to the second embodiment will be described with reference to FIG. 12 . FIG. 12 is a flowchart showing an example of the flow of discharge processing of the converter according to the second embodiment.

The process shown in FIG. 12 is performed after the control unit 26A receives a stop command from an external device or the like after the operation of the converter is finished.

26 A of control parts turn off the cutoff switch part 12 by the side of the 1st power supply 1 (step S301). Specifically, control unit 26</b>A turns off switch unit 12 to electrically disconnect first power supply 1 and converter 23 . Then, the process proceeds to step S302.

The control unit 26A turns off the cutoff switch unit 18 on the side of the second power supply 2 (step S302). Specifically, control unit 26</b>A turns off switch unit 18 to electrically disconnect second power supply 2 and converter 23 . Then, the process proceeds to step S303.

The control unit 26A turns on the discharge circuit unit 27 (step S303). Specifically, control unit 26</b>A turns on discharge circuit unit 27 to discharge the charge inside converter 23 . Then, the process proceeds to step S304.

The controller 26A waits for a predetermined time (step S304). Specifically, control unit 26A waits until the charge in converter 23 is discharged. Then, the process proceeds to step S305.

The control unit 26A determines whether or not the voltage inside the cutoff switch unit 18 on the side of the second power supply 2 is less than a predetermined value (step S305). Specifically, control unit 26A determines whether the voltage value detected by voltage detection unit 20 is less than a predetermined value. More specifically, control unit 26A determines whether the voltage value detected by voltage detection unit 20 is less than voltage V2 of second power supply 2 . If it is determined that the voltage inside the cutoff switch section 18 is less than the predetermined value (step S305; Yes), the process proceeds to step S306. If it is not determined that the voltage inside the cutoff switch section 18 is less than the predetermined value (step S305; No), the process proceeds to step S308.

When determined as Yes in step S305, the control section 26A determines whether or not the voltage inside the cutoff switch section 12 on the side of the first power supply 1 is less than a predetermined value (step S306). Specifically, control unit 26A determines whether the voltage value detected by voltage detection unit 14 is less than a predetermined value. More specifically, the control unit 26A determines whether or not the voltage value detected by the voltage detection unit 14 is less than the voltage V1 of the first power supply 1 . If it is determined that the voltage inside the cutoff switch section 12 is less than the predetermined value (step S306; Yes), the process proceeds to step S307. If it is not determined that the voltage inside the cutoff switch section 12 is less than the predetermined value (step S306; No), the process proceeds to step S308.

If determined as Yes in step S306, the control unit 26A turns off the discharge circuit unit 27 (step S307). Specifically, control unit 26</b>A turns off discharge circuit unit 27 to end the discharge process of converter 23 . Then, the processing of FIG. 12 ends.

If it is determined No in step S305 or if it is determined No in step S306, the control section 26A determines that the cut-off switch section 12 or cut-off switch section 18 is out of order (step S308). Specifically, when the determination in step S305 is No, the control unit 26A determines that the cut-off switch unit 18 has a short-circuit failure. 26 A of control parts determine with the cutoff switch part 12 having the short-circuit failure, when it determines with No by step S306. Then, the processing of FIG. 12 ends.

As described above, the second embodiment can discharge the charge inside the converter 23 after the operation of the converter 23 is finished. As a result, in the second embodiment, the state before the start of the converter 23 and the state after the end of the converter 23 can be the same. can appropriately detect the midpoint voltage between

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited by the contents of these embodiments. In addition, the components described above include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those within the so-called equivalent range. Furthermore, the components described above can be combined as appropriate. Furthermore, various omissions, replacements, or modifications of components can be made without departing from the gist of the above-described embodiments.

1 first power source 2 second power source 3, 4 fuse 10 control device 11, 17 current detection section 12, 18 cutoff switch section 13, 19 overcurrent detection section 14, 15, 20, 21, 254 voltage detection section 16, 22 output Capacitor 23 Converter 24 Switching element diagnosis unit 241 Diode 242, 252 Resistance element 25 Midpoint voltage detection unit 251 Zener diode 253 Voltage dividing circuit 26, 26A Control unit 27 Discharge circuit unit 30, 31 Cutoff switch control unit 33 Switching element control unit 34 Power control unit 35 Discharge circuit drive unit 100 Power supply system

Claims (4)

a high side switch element provided between the first power supply and the second power supply and having a drain terminal electrically connected to the power supply line; and a drain terminal electrically connected to the source terminal of the high side switch element. , and a low-side switch element having a source terminal electrically connected to a ground line;
a first cutoff switch unit having one end electrically connected to the positive electrode of the first power supply and the other end electrically connected to the drain of the high side switch element;
a second cutoff switch unit having one end electrically connected to the positive electrode of the second power supply and the other end electrically connected to the drain of the high side switch element;
a midpoint voltage detection unit that detects a midpoint voltage between the high side switch element and the low side switch element;
a first voltage detection unit that measures a voltage between the first cutoff switch unit and the converter;
a second voltage detection unit that measures the voltage between the first power supply and the first cutoff switch unit;
a third voltage detection unit that measures a voltage between the second cutoff switch unit and the converter;
a fourth voltage detector that measures the voltage between the second power supply and the second cutoff switch;
a discharge circuit unit having one end electrically connected to the drain terminal of the high side switch element and the other end electrically connected to the source terminal of the low side switch element;
a control unit for turning off the first cutoff switch unit and the second cutoff switch unit after the midpoint voltage detection unit detects the midpoint voltage and confirms the operation of the converter;
with
The control unit controls the discharge circuit unit based on the detection result of the first voltage detection unit and the detection result of the measurement value of the third voltage detection unit, and the voltage stored in the converter is to discharge an electric charge,
Control device. When the detection result of the first voltage detection unit and the detection result of the third voltage detection unit are equal to or greater than a predetermined threshold value, the control unit controls the discharge circuit unit to store the voltage inside the converter. to discharge the charged charge,
A control device according to claim 1 . The threshold of the detection result of the first voltage detection unit is set based on the detection result of the second voltage detection unit, and the threshold of the detection result of the third voltage detection unit is set based on the detection result of the fourth voltage detection unit. set by
3. A control device according to claim 2. a high side switch element provided between the first power supply and the second power supply and having a drain terminal electrically connected to the power supply line; and a drain terminal electrically connected to the source terminal of the high side switch element. , and a low side switch element having a source terminal electrically connected to a ground line, respectively, detecting a midpoint voltage between the high side switch element and the low side switch element; ,
After detecting the midpoint voltage and confirming the operation of the converter, a first cutoff switch having one end electrically connected to the positive electrode of the first power supply and the other end electrically connected to the drain of the high side switch element. and a second cut-off switch unit, one end of which is electrically connected to the positive electrode of the second power supply and the other end of which is electrically connected to the drain of the high-side switch element, to be turned off;
measuring a voltage between the first isolation switch unit and the converter;
measuring the voltage between the first power supply and the first cut-off switch;
measuring the voltage between the second isolation switch unit and the converter;
measuring the voltage between the second power supply and the second cut-off switch;
Based on the detection result of the voltage between the first cut-off switch section and the converter and the detection result of the voltage between the second cut-off switch section and the converter, the charge accumulated inside the converter is removed. discharging;
control methods, including;

Images