WO2015163415A1

WO2015163415A1 - Electrical device

Info

Publication number: WO2015163415A1
Application number: PCT/JP2015/062387
Authority: WO
Inventors: 和隆岩田
Original assignee: 日立工機株式会社
Priority date: 2014-04-26
Filing date: 2015-04-23
Publication date: 2015-10-29

Abstract

To ensure that an inverter circuit is not started when a connection fault or miswiring is present, and to make it possible to prevent the inverter circuit from being damaged, the present invention is provided with a motor (2), an inverter circuit (40) for driving the motor, and a control circuit (50) for controlling the inverter circuit (40). The inverter circuit (40) has a serial connection between high-side switching elements (Q1-Q3) and low-side switching elements (Q4-Q6), and the control circuit (50) is configured so as not to start the inverter circuit (40) when the voltage is irregular at the points of connection between the high-side switching elements (Q1-Q3) and the low-side switching elements (Q4-Q6).

Description

Electrical equipment

The present invention relates to an electric tool that drives a motor using an inverter circuit, and an electric device such as a washing machine.

In recent years, in various electric devices including electric tools, a configuration in which a motor such as a brushless motor is driven via an inverter circuit has become common. In this case, an inverter circuit that drives the motor and a control circuit that controls the inverter circuit may be physically separated, and a structure may be employed in which the two are connected by a wire harness. If there is a connection failure (misconnection, continuity failure, etc.), the inverter circuit may be damaged during operation of the inverter circuit due to the connection failure. Moreover, even when the wire harness is not used, there is a risk of failure due to incorrect wiring. For this reason, it is desirable to prevent the inverter circuit from being damaged by preventing the inverter circuit from starting in a state where there is a connection failure or incorrect wiring.

JP 2009-40178 A

Patent Document 1 mainly aims to detect motor drive coil abnormality by focusing on the motor current when the motor is driven by an inverter circuit. An object of the present invention is to provide an electrical device that can prevent the inverter circuit from being damaged by preventing the inverter circuit from being activated in a state where there is a connection failure or miswiring.

The first aspect of the present invention is an electrical device. The electric device includes a motor, an inverter circuit that drives the motor, and a control circuit that controls the inverter circuit, and the inverter circuit is connected in series to each other in a high-side switching element and a low-side switching element. And the control circuit is configured not to start the inverter circuit when at least one drive signal line of the switching element is defective in a state before starting the motor. .

In the first aspect, the inverter circuit has a connection point for detecting a voltage between the high-side switching element and the low-side switching element, and the control circuit is provided before starting the motor. The motor may be configured not to start when the voltage at the connection point is abnormal in the state. *

The second aspect of the present invention is also an electric device. The electric device includes a motor, an inverter circuit that drives the motor, and a control circuit that controls the inverter circuit, and the inverter circuit is connected in series to each other in a high-side switching element and a low-side switching element. The control circuit is configured not to start up the inverter circuit when the voltage at the connection point is abnormal.

In the first or second aspect, the high-side switching element is turned on in the off state of the low-side switching element to detect a voltage at a connection point between the high-side switching element and the low-side switching element. It may be a configuration. *

In the first or second aspect, a bootstrap capacitor is provided on the high-side switching element side, and the low-side switching element is turned on once to charge the bootstrap capacitor, The low-side switching element may be turned off and the high-side switching element may be turned on to detect the voltage at the connection point between the high-side switching element and the low-side switching element. *

In the first or second aspect, the voltage at the connection point between the high-side switching element and the low-side switching element may be detected when all the switching elements of the inverter circuit are off. . *

In the first or second aspect, the inverter circuit is mounted on a first board, the control circuit is mounted on a second board, and the first board and the second board are wiring components. It is preferable that the configuration be electrically connected.

In the first aspect, the inverter circuit has a connection point for detecting a voltage between the high-side switching element and the low-side switching element, and the control circuit is provided before starting the motor. The motor may be configured not to start when the voltage at the connection point is outside a predetermined range in the state. *

In the second aspect, the control unit may be configured not to start the motor when the voltage at the connection point is outside a predetermined range. *

It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

According to the electric device of the present invention, the control circuit has a function of detecting the voltage at the connection point between the high-side switching element and the low-side switching element in the inverter circuit, and the detection result of the voltage at the connection point is By preventing the inverter circuit from starting in the case of an abnormality, it is possible to avoid damage to the inverter circuit.

1 is an electric system diagram of an electric tool according to an embodiment of an electric device according to the present invention. The side view of an electric tool. The circuit diagram which shows the switching element for one phase of an inverter circuit, and its gate drive signal preparation circuit part in embodiment. The flowchart of the 3-phase operation | movement check of the said inverter circuit. The flowchart of the operation | movement check for 1 phase of the said inverter circuit. The flowchart which shows the other example of the operation | movement check for 1 phase of the said inverter circuit.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

An electric tool will be described as an embodiment of an electric apparatus according to the present invention with reference to FIGS. 1 and 2. In FIG. 1, the electric system of the electric tool 1 includes a three-phase brushless DC motor 2, a battery pack 30 as a DC power source, an inverter circuit 40 that drives the motor 2, and a control circuit 50 that controls the inverter circuit 40. Have. The inverter circuit 40 is supplied with DC power from the battery pack 30, and a predetermined DC power supply voltage is also supplied to the control circuit 50 although connection is omitted. *

As shown in FIG. 2, the three-phase brushless DC motor 2 includes a rotor (rotor) 2a and a stator winding (armature winding) 2d. The rotor 2a has N-pole and S-pole permanent magnets (magnets) 2b extending in the direction of the rotation shaft 2e. The stator (stator) 2c has a cylindrical outer shape, and is a so-called internal magnet arrangement type motor having a stator winding 2d wound around a tooth portion thereof. The stator winding 2d is wound around the stator 2c via an insulating layer 2f made of a resin material. The stator winding 2d of each phase (U phase, V phase, W phase) is star-connected.

In the vicinity of the rotor 2a, three rotational position detecting elements (Hall elements or the like) 60 are arranged every 60 ° in the rotational direction, and the rotational position of the rotor 2a is detected electromagnetically. The rotational position detection element 60 is mounted on the inverter circuit board 3, for example. *

The inverter circuit 40 includes six switching elements Q1 to Q6 such as FETs connected in a three-phase bridge format. Switching elements Q1 to Q3 are high-side switching elements, switching elements Q4 to Q6 are low-side switching elements, and the connection points between the high-side switching elements and the low-side switching elements in each phase are star-connected. The phase winding, the V phase, and the W phase are respectively connected to the stator winding 2d. *

The control circuit 50 includes a calculation unit 51, a control signal output circuit (gate driver) 52, a rotor position detection circuit 53 that receives detection signals from the three rotation position detection elements 60, and a motor rotation number detection circuit 54. Including at least. The rotor position detection signal of the rotor position detection circuit 53 is input to the calculation unit 51 and the motor rotation number detection circuit 54, and the motor rotation number detection signal of the motor rotation number detection circuit 54 is also input to the calculation unit 51.

Although not shown, the calculation unit 51 includes a CPU for outputting a control signal based on a processing program and data, a ROM for storing a processing program and control data for executing a control flow as described later, and data. The microcomputer includes a RAM for temporarily storing, a timer for counting time, and the like, and executes various processes based on the processing program and data. The rotor position detection circuit 53 detects the rotation position of the rotor 2 a based on the output signals of the three rotation position detection elements 60 and outputs the position information of the rotor 2 a to the calculation unit 51. The rotation speed detection circuit 54 detects the rotation speed of the motor 2 from the time interval of signals output at regular intervals from the three rotation position detection elements 60. *

Based on the rotor position detection signal from the rotor position detection circuit 53 and the rotation speed detection signal from the rotation speed detection circuit 54, the calculation unit 51 controls the control signal output circuit 52 to turn on the switching elements Q1 to Q6. For this reason, the control signal output circuit 52 applies PWM drive signals H1 to H6 to the gates of the switching elements Q1 to Q6.

As shown in FIG. 2, a switch trigger 7 is disposed near the upper end of the handle portion 6b of the housing 6, and the trigger operation portion 7a of the switch trigger 7 protrudes from the handle portion 6b while being biased by a spring force. . When the operator pushes the trigger operation portion 7a backward, the trigger push-in amount (operation amount) can be adjusted and the rotation speed of the motor 2 can be controlled. The amount of trigger pressing by the switch trigger 7 is reflected in the PWM duty of the PWM drive signals H1 to H6 that drive the switching elements Q1 to Q6. However, in general, PWM control is performed to change the pulse width of the drive signals H1 to H3 of the high side switching elements Q1 to Q3 while keeping the pulse width of the drive signals H4 to H6 of the low side switching elements Q4 to Q6 constant. Do.

As shown in FIG. 2, the inverter circuit board (first board) 3 on which the inverter circuit 30 is mounted is disposed behind the motor 2 housed in the body portion 6 a of the housing 6, and the control circuit 50 is mounted on the control circuit board. The circuit board (second board) 4 is housed in the lower part of the handle 6b of the housing 6, and the inverter circuit board 3 and the control circuit board 4 are electrically connected via a wire harness 80 as a wiring component. Yes.

In the present embodiment, the high-side switching element of each phase (U phase, V phase, W phase) is detected for the purpose of detecting a connection failure (misconnection, conduction failure, etc.) to the

substrates

3 and 4 of the wire harness 80. And a voltage obtained by dividing the voltage at the connection point between the low-side switching element and the low-side switching element through a voltage dividing resistor. That is, the voltage Uv ′ obtained by dividing the voltage Uv (the terminal voltage of the U-phase stator winding 2d) between the high-side switching element Q1 and the low-side switching element Q4 by the voltage dividing resistors R1 and R2; The voltage Vv ′ obtained by dividing the voltage Vv (the terminal voltage of the V-phase stator winding 2d) of the high-side switching element Q2 and the low-side switching element Q5 by the voltage dividing resistors R3 and R4 and the high side The voltage Wv ′ obtained by dividing the voltage Wv (the terminal voltage of the W-phase stator winding 2d) of the switching element Q3 and the low-side switching element Q6 by the voltage dividing resistors R5 and R6 is the calculation unit 51. Has been entered. The voltage dividing resistors R1 and R2, the voltage dividing resistors R3 and R4, and the voltage dividing resistors R5 and R6 have the same voltage dividing ratio (for example, 1/5), and the divided voltage Uv ′, voltage Vv ′, and The voltage Wv ′ is set to a voltage range suitable for processing in the calculation unit 51.

The mechanical structure of the electric power tool 1 (the illustrated example is a driver drill) will be described with reference to FIG. The electric tool 1 includes a housing 6 having a body portion 6a and a handle portion 6b. The brushless motor 2 is housed in the body portion 6a, and a spindle (output shaft) is transmitted by a power transmission portion 25 that transmits the driving force of the motor 2. ) A rotational force is applied to a tip tool (not shown) such as a screwdriver or a drill that is detachably held by the chuck (tip tool attaching portion) 28 attached to 8. The stator 2c of the motor 2 is fixed to the body portion 6a.

An inverter circuit board 3 on which an inverter circuit 40 for driving the motor 2 is mounted is accommodated on the rear side of the body portion 6a. The intermediate portion and the front side of the body portion 6a are arranged in the direction of the rotating shaft 2e of the motor 2. A speed reduction mechanism portion 26 for transmitting the rotational force and reducing the rotational speed of the motor 2 and a clutch mechanism portion 27 for transmitting the rotational torque obtained at the output shaft of the speed reduction mechanism portion 26 to the spindle 8 are housed. The clutch mechanism 27 is coupled so as to transmit the rotational force of the speed reduction mechanism 26 to the spindle (output shaft) 8. The clutch mechanism unit 27 includes a dial (clutch dial) 5 for mode switching and torque adjustment, and the dial 5 is configured so that an operator can set a driver mode or a drill mode. Instead of the clutch mechanism 27, a normal impact mechanism may be provided.

A cooling fan 24 is coaxially provided on the front side of the motor 2, and an exhaust port (ventilation port) is formed in the body portion 6a in the vicinity of the cooling fan 24, although not shown. An intake port (ventilation port) 21 is formed at the rear end portion of the body portion 6a. A passage 23 extending from the intake port 21 to an exhaust port formed in the vicinity of the cooling fan 24 serves as a cooling air flow passage. Thus, the temperature rise of the switching elements Q1 to Q6 mounted on the inverter circuit board 3 and the temperature rise of the stator winding 2d of the motor 2 are suppressed.

The inverter circuit board 3 has a disk-like wiring board and covers one end side (rear side) of the stator 2c of the motor 2 entirely. On the other hand, a dustproof cover 22 is provided on the other end side (front side) of the stator 2 c and covers the other end side surface of the stator 2 c, similarly to the inverter circuit board 3. Both the inverter circuit board 3 and the dustproof cover 22 form a dustproof structure (sealed structure) that closes or seals the rotor 2a together with the stator 2c. Thereby, the penetration | invasion of the dust to the motor 2 can be prevented.

A switch trigger 7 is disposed in the vicinity of the upper end of the handle portion 6b, and the trigger operation portion 7a of the switch trigger 7 projects from the handle housing portion 6b while being biased by a spring force. When the operator pushes the trigger operation portion 7a backward, the trigger push-in amount (operation amount) can be adjusted and the rotation speed of the motor 2 can be controlled. *

A battery pack 30 serving as a driving power source for the motor 2 is detachably attached to the lower end portion of the handle portion 6b. A control circuit board 4 on which a control circuit 50 for controlling the inverter circuit 40 of the motor 2 is mounted is provided above the battery pack 30. The battery pack 30 is electrically connected so as to supply drive power to the switch trigger 7 and the control circuit board 4 and further to supply drive power to the inverter circuit board 3.

FIG. 3 is a circuit diagram showing a switching element for one phase of the inverter circuit 40 and a gate drive signal generation circuit portion thereof. A bootstrap capacitor C1 required when N-type MOSFETs are used as the switching elements Q1 to Q6. In addition, a diode D1 for charging it is added to the gate drive signal generation circuit of the high-side switching elements Q1 to Q3. The resistors R7 to R10 are inserted in the gate circuits of the high side switching elements Q1 to Q3 and the low side switching elements Q4 to Q6, and the resistor R11 is connected between the drain and source of the high side switching elements Q1 to Q3. Yes. The resistor R11 has such a high resistance that power consumption can be ignored. Even when all the switching elements Q1 to Q6 are turned off, the group of the voltage dividing resistors R1, R2 and the voltage dividing resistors R3, R4 in FIG. The terminal voltage of the stator winding 2d of each phase (U-phase, V-phase, W-phase) can be detected by the calculation unit 51 via the set of voltage dividing resistors R5 and R6. The high side control signal output from the calculation unit 51 to the control signal output circuit (gate driver) 52 is a signal for generating drive signals H1 to H3 to be applied to the gates of the high side switching elements Q1 to Q3. The low side control signal is a signal for generating drive signals H4 to H6 to be applied to the gates of the low side switching elements Q4 to Q6.

Here, the operation of the bootstrap capacitor C1 will be briefly described. Since the maximum value of the terminal voltage of the stator winding 2d of each phase (U phase, V phase, W phase) of the motor 2 is the DC supply voltage Vcc, the high side switching elements Q1 to Q3 are turned on. Therefore, a gate voltage higher than the DC supply voltage Vcc is required as the drive signals H1 to H3 applied to the gate. Therefore, by charging the bootstrap capacitor C1 in the direction shown in FIG. 3 while the low-side switching elements Q4 to Q6 are on, the low-side switching elements Q4 to Q6 are turned off using this charging voltage. During the period, drive signals H1 to H3 higher than the DC supply voltage Vcc (higher than the source potential of the high side switching elements Q1 to Q3) can be applied to the gates of the high side switching elements Q1 to Q3. *

The operation check of the electric system of the electric power tool 1 will be described with reference to the flowcharts of FIGS. 4 and 5. *

FIG. 4 shows the flow of the operation check of the entire electric system. After the trigger operation unit 7a of the switch trigger 7 is operated and the control circuit 50 starts the control, before the inverter circuit 40 is started (before the motor 2 is normally operated). ) A U-phase operation check is performed in step # 1, then a V-phase operation check is performed in step # 2, and finally a W-phase operation check is performed in step # 3. The order of the phase operation check can be arbitrarily changed.

FIG. 5 shows the flow of each phase operation check for the U, V, and W phases. However, this is a case where N-type MOSFETs are used as the switching elements Q1 to Q6. First, at the start of the phase operation check, the low side (LOW side) MOSFET is once turned on at step # 10, and as a result, the bootstrap capacitor charging at step # 11 is performed. Thereafter, the low side MOSFET is turned off in step # 12, and the high side (HIGH side) MOSFET is turned on in step # 13. In step # 14, the calculation unit 51 determines whether the terminal voltage of the stator winding 2d (the voltage at the connection point between the high-side MOSFET and the low-side MOSFET) is the DC supply voltage Vcc ± 1V. When the terminal voltage is the DC supply voltage Vcc ± 1 V which is a predetermined voltage range (in the case of YES), the inverter circuit 40 is normal in step # 15 (that is, there is no conduction failure of the drive signal line to the gate of the low side MOSFET, It is determined that the bootstrap capacitor is charged and there is no conduction failure of the drive signal line to the high-side MOSFET gate. In step # 16, the high-side MOSFET is turned off, and the operation of the phase to be checked End the check. If the terminal voltage is not the DC supply voltage Vcc ± 1V (in the case of NO), it is determined in step # 17 that the inverter circuit 40 is abnormal, the high-side MOSFET is turned off in step # 16, and the phase to be checked is checked. End the operation check. When it is determined that the inverter circuit 40 is abnormal, the calculation unit 51 controls so that the subsequent normal operation of the inverter circuit 40 cannot be performed (so that the inverter circuit 40 is not activated), and the abnormality is notified to the outside. Output a signal. If no abnormality is detected in the inverter circuit 40 as a result of the all-phase check of the U, V, and W phases, the inverter circuit 40 is activated by the calculation unit 51, and the normal operation is performed based on the PWM drive signals H1 to H6. The rotation control of the motor 2 is performed.

The operation check of FIGS. 4 and 5 can detect an operation failure of the inverter circuit 40 (for example, a conduction failure of the drive signal line to the gate of the switching element), and the inverter circuit 40 is switched by performing motor control in the failure state. It is possible to prevent the elements and the like from being damaged. In particular, when the inverter circuit board 3 on which the inverter circuit 40 is mounted and the control circuit board 4 on which the control circuit 50 is mounted are connected by a wire harness 80 as a wiring component, the connection failure of the wire harness during assembly ( Incorrect connection, poor conduction, etc.) caused an operation failure of the inverter circuit 40, and although the inverter circuit 40 itself was a normal product, the inverter circuit 40 was sometimes damaged. Inconvenience can be prevented. The same effect can be expected when wiring components other than the wire harness (for example, a multi-core cable) are used.

FIG. 6 shows another example of the operation check for each phase of the U, V, and W phases, and steps # 20 to # 23 are added to the steps of FIG. ) Is detected. First, all MOSFETs are turned off in step # 20 by starting phase operation check. In step # 21, the terminal voltage of the stator winding 2d (voltage at the connection point between the high-side MOSFET and the low-side MOSFET) is within a predetermined voltage range, that is, DC supply. Whether the voltage is Vcc ± 1 V is determined by the calculation unit 51. If the terminal voltage is the DC supply voltage Vcc ± 1 V (in the case of YES), it is determined in step # 22 that the inverter circuit 40 is normal, and the same operation check as in FIG. If the terminal voltage is not the DC supply voltage Vcc ± 1V (in the case of NO), it is determined in step # 23 that the inverter circuit 40 is abnormal. When it is determined that the inverter circuit 40 is abnormal, the calculation unit 51 controls so that the subsequent normal operation of the inverter circuit 40 cannot be performed (so that the inverter circuit 40 is not activated), and the abnormality is notified to the outside. Output a signal.

According to the operation check in FIG. 6, it is possible to detect a defect in the inverter circuit 40 itself and a connection failure in the wire harness 80 more carefully. *

According to the present embodiment, the following effects can be achieved. *

(1) The calculation unit 51 of the control circuit 50 detects the voltage at the connection point between the high-side switching elements Q1 to Q3 and the low-side switching elements Q4 to Q6 (terminal voltage of the stator winding 2d of each phase). Therefore, when the detection result of the voltage at the connection point is abnormal (the voltage at the connection point is out of the predetermined range), the inverter circuit 40 can be prevented from being damaged by performing control that does not start the inverter circuit 40.

(2) In particular, the inverter circuit 40 is mounted on the inverter circuit board 3 as the first board, the control circuit 50 is mounted on the control circuit board 4 as the second board, and the inverter circuit board 3 and the control circuit board 4 are mounted. Are electrically connected by wiring components such as the wire harness 80, etc., even if the inverter circuit itself is normal, the inverter circuit 40 cannot operate normally due to a connection failure of the wire harness 80 or the like. . In such a case, when the inverter circuit 40 is started for normal motor driving, the inverter circuit 40 may be damaged, but this can be prevented beforehand. *

(3) The low side switching elements Q4 to Q6 are once turned on to charge the bootstrap capacitor C1, and then the low side switching elements Q4 to Q6 are turned off and the high side switching elements Q1 to Q3 are turned on to be high. By using an operation check flow for detecting the voltage at the connection point between the side switching elements Q1 to Q3 and the low side switching elements Q4 to Q6 (terminal voltage of the stator winding 2d of each phase), the switching elements Q1 to Q6 Even if an N-type MOSFET is used, the operation of the inverter circuit 40 can be checked.

(4) Furthermore, by detecting the voltage at the connection point between the high-side switching element and the low-side switching element in the OFF state of all the switching elements Q1 to Q6 of the inverter circuit 40, the inverter circuit 40 itself is defective. For example, a short circuit failure of the low side switching element can be detected.

The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described. *

In the above embodiment, P-type MOSFETs may be used as the switching elements Q1 to Q6. In this case, since the drive signals H1 to H3, which are the gate signals of the high side switching elements Q1 to Q3, have a voltage value lower than the DC supply voltage Vcc, a bootstrap capacitor is not used. For this reason, the step for charging the bootstrap capacitor in step # 10 and step # 11 in FIGS. 5 and 6 is omitted. *

Although the said embodiment illustrated the electric tool, this invention is applicable if it is an electric equipment which controls motors, such as not only an electric tool but a high-pressure washing machine, with an inverter circuit.

DESCRIPTION OF SYMBOLS 1 ... Electric tool, 2 ... Brushless DC motor, 2a ... Rotor, 2b ... Permanent magnet, 2c ... Stator, 2d ... Stator winding, 2e ... Rotary shaft, 3 ... Inverter circuit board, 4 ... Control circuit board, DESCRIPTION OF SYMBOLS 6 ... Housing, 7 ... Switch trigger, 7a ... Trigger operation part, 25 ... Power transmission part, 26 ... Deceleration mechanism part, 27 ... Clutch mechanism part, 28 ... Chuck (tip tool attachment part), 30 ... Battery pack, 40 ... Inverter circuit, 50 ... control circuit, 51 ... arithmetic unit, 52 ... control signal output circuit, 53 ... rotor position detection circuit, 54 ... rotational speed detection circuit, 60 ... rotational position detection element, C1 ... bootstrap capacitor, D1 ... Diodes, H1 to H6 ... Drive signals, Q1 to Q6 ... Switching elements, R1 to R11 ... Resistance

Claims

A motor, an inverter circuit that drives the motor, and a control circuit that controls the inverter circuit, the inverter circuit having a high-side switching element and a low-side switching element connected in series with each other; An electrical apparatus comprising: the control circuit configured not to start the inverter circuit when at least one drive signal line of the switching element is in a poor conduction state before starting the motor.
The inverter circuit has a connection point for detecting a voltage between the high-side switching element and the low-side switching element, and the control circuit has a voltage at the connection point in a state before starting the motor. The electric device according to claim 1, wherein the motor is not activated when the motor is abnormal.
A motor, an inverter circuit that drives the motor, and a control circuit that controls the inverter circuit, the inverter circuit having a voltage between a high-side switching element and a low-side switching element connected in series with each other An electrical apparatus having a connection point for detecting the inverter circuit, wherein the control circuit is configured not to start the inverter circuit when the voltage at the connection point is abnormal.
4. A voltage at a connection point between the high-side switching element and the low-side switching element is detected by turning on the high-side switching element in an off state of the low-side switching element. Electrical equipment as described in any one of.
A bootstrap capacitor is provided on the high-side switching element side. The low-side switching element is turned on once to charge the bootstrap capacitor, and then the low-side switching element is turned off and the high-side switching element is turned on. 5. The electrical device according to claim 1, wherein a side switching element is turned on to detect a voltage at a connection point between the high-side switching element and the low-side switching element. 6.
6. The voltage at a connection point between the high-side switching element and the low-side switching element is detected in an off state of all the switching elements of the inverter circuit. The electrical equipment described.
The inverter circuit is mounted on a first board, the control circuit is mounted on a second board, and the first board and the second board are electrically connected by wiring components. The electrical device according to any one of claims 1 to 6.
The electric device according to claim 2, wherein the control unit is configured not to start the motor when a voltage at the connection point is outside a predetermined range.