DC power supply unit

Abstract

A direct current power supply device (1, 2) comprising: a first conversion unit (10) which is connected to an external AC power supply (3); a second conversion unit (30) connected to an external power tool (70); and a cable (5) connecting the first conversion unit (10) and the second conversion unit (30), wherein the first conversion unit (10) comprises a power factor correction circuit (12), converts an AC voltage of a first voltage value input from the external AC power supply (3) into a DC voltage of a second voltage value higher than the first voltage value, and outputs the DC voltage of the second voltage value to the cable (5); the second conversion unit (30) converts an output voltage of the first conversion unit (10) input via the cable (5) into a DC voltage with a third voltage value that is lower than the second voltage value, and outputs the DC voltage with the third voltage value to the external power tool (70), the first conversion unit (10) includes a shutdown circuit (13), which, when the cable (5) is interrupted, switches off the output of the DC voltage to the cable (5), the first conversion unit (10) comprises a first cooling fan (17) which generates cooling air within the first conversion unit (10); the second conversion unit (30) includes a second cooling fan (37), which generates cooling air within the second conversion unit (30), the first voltage value is 80 V or more and less than 260 V, the second voltage value is 200 V or more and less than 500 V and the third voltage value is 0 V or more and less than 70 V.

Description

Technical area

[0001] The present invention relates to a DC power supply device that converts an alternating voltage supplied from an alternating current network into a DC voltage and supplies the DC voltage to a power tool. Related Art

[0002] A DC power supply device, as shown in the following patent document 1, comprises a conversion unit that converts an AC voltage of 100 V, supplied by a commercial power supply or the like, into a DC voltage with a desired voltage value lower than 100 V and outputs the DC voltage; an adapter that can be connected to a battery pack terminal of a cordless power tool; and a cable that connects the conversion unit and the adapter. For convenience of connection to the power tool's battery pack terminal, the adapter needs to be small and lightweight and essentially the same shape as a battery pack that can be connected to the power tool's battery pack terminal in place of the adapter.Therefore, circuit elements such as a rectifier circuit, a smoothing circuit and a transformer are provided in a conversion unit separate from the adapter.

[0003] Patent document 2 shows a configuration in which a main unit includes a switching power source that converts a 100 V AC input from a commercial AC power source to DC and outputs the DC.

[0004] Patent document 3 discloses a configuration in which an adapter includes a voltage converter that converts the input 12-30V DC to 7-24V DC and outputs the DC.

[0005] Patent document 4 discloses a machine control and an isolation transformer that converts the alternating current input from the power grid into direct current and outputs the direct current.

[0006] Similarly, patent document 5 describes that the power supply includes a PFC control circuit.

[0007] Patent document 6 shows a configuration in which the power supply includes a noise filter that converts the AC input from a commercial AC power supply to DC, rectifier / smoothing circuits and a transformer. State of the art documents Patent documents Patent document 1: JP 2005 - 278 375 A Patent document 2: US 2004 / 0 232 892 A1 Patent document 3: US 5,929,597 A Patent Document 4: CN 1 01 166 003 A Patent document 5: DE 198 16 684 A1 Patent document 6: JP 2015 -82 931 A SUMMARY OF THE INVENTION Problems to be solved by the invention

[0008] When alternating current (AC) is converted to direct current (DC) in the conversion unit and output at a desired low voltage, a large amount of current flows in the cable from the conversion unit to the adapter, resulting in significant power loss along the cable. In a DC power supply device delivering DC power to a high-powered power tool, this power loss is particularly pronounced when the conversion unit outputs a low voltage.

[0009] One objective of the present invention is to provide a DC power supply device that is capable of suppressing power losses. Means of solving the problems

[0010] One aspect of the present invention is a DC power supply device. The DC power supply device comprises: a first conversion unit connected to an external AC power supply; a second conversion unit connected to an external power tool; and a cable connecting the first and second conversion units. The first conversion unit contains a power factor correction circuit, converts an AC voltage of a first voltage value, input from the external AC power supply, into a DC voltage of a second voltage value, which is higher than the first voltage value, and outputs the DC voltage of the second voltage value to the cable.The second conversion unit converts an output voltage from the first conversion unit, which is input via the cable, into a DC voltage of a third voltage value that is lower than the second voltage value, and outputs the DC voltage of the third voltage value to the external power tool.

[0011] The first conversion unit includes a disconnect circuit that interrupts the DC voltage output to the cable if the cable is broken. The first conversion unit also includes a cooling fan that generates cooling air within the unit. The second conversion unit includes a second cooling fan that generates cooling air within the unit. The first voltage is 80 V or more and less than 260 V, the second voltage is 200 V or more and less than 500 V, and the third voltage is 0 V or more and less than 70 V.

[0012] The second conversion unit can be connected to a battery pack connector of the external power tool instead of the battery pack, which is powered by the energy of a detachably attached battery pack.

[0013] The second conversion unit can include a feed signal generator that produces a feed signal indicating that a DC voltage is being supplied to the second conversion unit via the cable. The cable can include a feed signal transmission line that carries the feed signal from the second conversion unit to the first conversion unit. The first conversion unit can include a shutdown circuit that, if the feed signal disappears from the feed signal transmission line while the DC voltage is being output to the cable, shuts off the DC voltage output to the cable.

[0014] The first conversion unit may contain a first control unit that is connected to the feed signal transmission line and controls the shutdown circuit.

[0015] The first control unit can put the shutdown circuit into a shutdown state if an abnormality is detected.

[0016] The second conversion unit can contain a second control unit, and the second control unit can transmit an abnormality detection signal to the external power tool connected to it when the abnormality is detected.

[0017] The first conversion unit may include a reset terminal that resets the first control unit to an initial state, and the first control unit may set the shutdown circuit to a non-shutdown state when it is reset to the initial state.

[0018] The shutdown circuit may contain a switching element that is provided in a path of an alternating current of the first conversion unit.

[0019] The first conversion unit can contain a first control unit that controls the drive of the first cooling fan. The second conversion unit can contain a second control unit that controls the drive of the second cooling fan.

[0020] The second conversion unit can lower its output voltage if its output current increases.

[0021] The first conversion unit may contain: a first input section connected to the external AC power supply, into which the AC voltage of the first voltage value is input; the power factor correction circuit connected to the first input section; a rectifier circuit connected to an output side of the power factor correction circuit; a boost circuit that increases an output voltage of the rectifier circuit; a smoothing circuit that smooths an output voltage of the boost circuit; and a first output section connected to the cable that outputs the DC voltage of the second voltage value, which is output by the smoothing circuit, to the cable.

[0022] The second conversion unit may include: a second input part connected to the cable into which the DC voltage of the second voltage value is input; a transformer circuit that transforms the DC voltage input to the second input part and outputs the DC voltage of the third voltage value, which is lower than the second voltage value; and a second output part connected to the external power tool that outputs a voltage from the transformer circuit to the external power tool.

[0023] The transformer circuit can include an isolation transformer and a switching element connected to a primary side of the isolation transformer.

[0024] A DC power supply device may comprise: a first conversion unit connected to an external AC power supply; a second conversion unit connected to an external power tool; and a cable connecting the first and second conversion units. The first conversion unit may include a power factor correction circuit that converts an AC voltage of a first voltage value, input from the external AC power supply, into a DC voltage of a second voltage value higher than the first voltage value, and outputs the DC voltage of the second voltage value to the cable.The second conversion unit can convert an output voltage from the first conversion unit, input via the cable, into a third DC voltage of a lower value than the second voltage, and output this third DC voltage to the external power tool. The first conversion unit may include a shutdown circuit that, if an abnormality is detected, cuts off the DC output to the cable. The first conversion unit may include a cooling fan that generates cooling air within the unit. The second conversion unit may include a second cooling fan that generates cooling air within the unit. The first voltage value can be 80 V or more and less than 260 V, the second voltage value 200 V or more and less than 500 V, and the third voltage value 0 V or more and less than 70 V.

[0025] The first cooling fan can be located at the rear end and within the first conversion unit. The first conversion unit can include a first inlet port located at the front and a first exhaust port located at the rear. The cable can be connected to the front end of the first conversion unit.

[0026] The first conversion unit may include an electrolytic capacitor and a rectifier circuit arranged between the first input terminal and the first exhaust terminal in a front-to-back direction of the DC power supply device.

[0027] The second cooling fan can be provided at a rear end and within the second conversion unit, the second conversion unit comprising: second inlet openings provided on both side surfaces of the second conversion unit; and a second outlet opening provided on a rear part of the second conversion unit.

[0028] The second conversion unit may include: an isolation transformer; and two fins arranged on either side of the isolation transformer to guide the cooling air drawn in through the second inlet openings.

[0029] The DC power supply device may further include a power cord that is arranged between the first conversion unit and an external AC power supply. The length of this cable may be greater than the length of the mains cable.

[0030] Furthermore, any combination of the above-mentioned components and those obtained by implementing the expression of the present invention in methods or systems, and so forth, are also disclosed as aspects of the present invention. Effects of the invention

[0031] According to the present invention, a DC power supply device can be provided which is capable of suppressing power loss. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a side view of a power tool 70 to which a DC power supply device 1 and a second conversion unit 30 thereof are connected according to embodiment 1 of the present invention. Fig. Figure 2 is a side view of the power tool 70, which is equipped with a battery pack 80. Fig. Figure 3 is a top view of the DC power supply device 1, in which a first conversion unit 10 and the second conversion unit 30 have their respective upper housings opened. Fig. Figure 4 is a top view showing an internal configuration of the first conversion unit 10. Fig. Figure 5 is a top view showing an internal configuration of the second conversion unit 30. Fig. Figure 6 is a circuit block view of the DC power supply device 1 and the power tool 70. Fig. Figure 7 is a diagram showing an example of a relationship between output current and output voltage of the second conversion unit 30 and a relationship between output current and output voltage of the battery pack 80. Fig. Figure 8 is a circuit block view of a DC power supply device 2 and the power tool 70 according to embodiment 2 of the present invention. DESCRIPTION OF THE EXECUTION FORMS

[0032] Preferred embodiments of the present invention are described in detail below with reference to the drawings. Furthermore, the same or equivalent components, elements, and so forth shown in the drawings are designated by the same reference numerals, and repeated descriptions are duly omitted. Moreover, the exemplary embodiments do not limit the invention but are to be understood as illustrative, and all features and combinations thereof described in the exemplary embodiments are not essential to the invention.

[0033] (Version 1) With reference to Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. Section 7 describes a DC power supply device 1 according to embodiment 1 of the present invention. A front-back direction of the DC power supply device 1 is defined by Fig. 3 defined. The DC power supply device 1 comprises a first conversion unit 10, a second conversion unit 30, and a cable 5. The first conversion unit 10 is connected to an external AC power supply via a power supply cable 11. The second conversion unit 30 is detachably connected to a battery pack terminal 75 of a power tool 70. A battery pack 80 can also be detachably connected to the battery pack terminal 75 of the power tool 70, as shown in Fig. Figure 2 shows that when an operator activates a trigger switch 71 of the power tool 70, drive energy is supplied to the power tool 70 from the DC power supply device 1 or the battery pack 80. Although the power tool 70 in the illustrated example is a rotary hammer, the type of power tool is not limited as long as it is a power tool to which the battery pack 80 is detachably connected. The cable 5 connects the first conversion unit 10 and the second conversion unit 30. The cable 5 is preferably longer than the power supply cable 11. Because the cable 5 is sufficiently long, there is no need to lift the first conversion unit 10 from the ground or similar surface while working with the power tool 70, nor does the operator have to bear the weight of the first conversion unit 10, thus improving operational efficiency.

[0034] As in Fig. As shown in Figure 3, a first cooling fan 17 is located at a rear end and inside the first conversion unit 10. A second cooling fan 37 is located at the rear end and inside the second conversion unit 30. The cooling airflow generated by the first cooling fan 17 and the second cooling fan 37 is in Fig. 3 shown by arrows. The cooling air generated by the first cooling fan 17 is drawn in through an inlet port 26, which is provided on a front part of a housing of the first conversion unit 10, flows forward while cooling each component of the first conversion unit 10, and is expelled through an exhaust port 27, which is provided on a rear part of the housing.The cooling air generated by the second cooling fan 37 is drawn in through inlet ports on both side surfaces of a housing of the second conversion unit 30, cools each component on both side surfaces of the second conversion unit 30 and inside the second conversion unit 30 as it is guided forward through ribs 41 and 42, flows from front to back in a middle part of the housing while cooling each component of a middle part of the second conversion unit 30 in a lateral direction, and is discharged from an exhaust port at a rear part of the housing.

[0035] As in Fig. As shown in Figure 4, the first conversion unit contains 10 components, such as an electrolytic capacitor C1, a diode D1, a switching element Q1, a diode bridge 14, a TRIAC 13 as a switching element, and an inductor L1. As shown in Fig. As shown in Figure 5, the second conversion unit contains 30 components such as the diodes D2 and D3, the fins 41 and 42, the electrolytic capacitors C2 and C3, an isolation transformer 31 and a switching element 32.

[0036] Fig. Figure 6 is a circuit block view of the DC power supply device 1 and the power tool 70. In the first conversion unit 10, two terminals connected to an external AC power supply 3 define a first input section. Among the connection terminals to the cable 5, two terminals (a positive (+) terminal 10b and a negative (-) terminal 10c) connected to an output terminal of a boost and smooth circuit 25 define a first output section. The first conversion unit 10 includes a power factor correction circuit 12, the TRIAC 13 as a shutdown circuit, the diode bridge 14 as a rectifier circuit, and the boost and smooth circuit 25. An input terminal of the power factor correction circuit 12 is connected to the AC power supply 3. For example, a peak value (first voltage value) of an AC voltage input from the AC power supply 3 is 80 V or more and less than 260 V.

[0037] An input terminal of the diode bridge 14 is connected to an output terminal of the power factor correction circuit 12. The TRIAC 13 is provided in a current path between the power factor correction circuit 12 and the diode bridge 14. The TRIAC 13 is designed to switch the output of the first conversion unit 10 on and off. The diode bridge 14 rectifies an output current of the power factor correction circuit 12. The boost and smoothing circuit 25 boosts an output voltage of the diode bridge 14. In the boost and smoothing circuit 25, the inductor L1, the diode D1, the switching element Q1, and the driver circuit 22 form a boost circuit. The electrolytic capacitor C1 forms a smoothing circuit that smooths an output voltage of the boost circuit. A voltage value (second voltage value) of a DC voltage output by the boost and smoothing circuit 25, i.e.The output voltage of the first conversion unit 10 is, for example, 200 V or more and less than 500 V. The second voltage value is higher than the first voltage value.

[0038] In the first conversion unit 10, a sensing resistor R1 is provided in a path of an output current of the boost and smoothing circuit 25 (an output current of the first conversion unit 10). An auxiliary power supply 15 converts the output voltage of the diode bridge 14 into an operating voltage (e.g., DC 5V) of a computing unit 20 or the like. A current sensing circuit 16 detects the output current of the boost and smoothing circuit 25 based on a voltage across the sensing resistor R1 and feeds it back to the computing unit 20. A temperature sensing circuit 19 contains a temperature sensing element, such as a thermistor, detects a temperature in the first conversion unit 10, and feeds it back to the computing unit 20. The computing unit 20 is an example of a first control unit and contains a microcontroller.The processing unit 20 controls the first cooling fan 17 according to a temperature sensing value from the temperature sensing circuit 19. Furthermore, the processing unit 20 switches off the TRIAC 13 and interrupts the output of the first conversion unit 10 if an abnormal temperature is detected by the temperature sensing circuit 19, if an abnormal current is detected by the current sensing circuit 16, or if a break in cable 5 is detected. One end of a resistor R2 is connected to a power supply line to which an output voltage from the auxiliary power supply 15 is applied. The other end of resistor R2 is connected to the processing unit 20 and also, via an abnormal detection terminal 10a, to a feed signal transmission line 5a of cable 5. That is, the processing unit 20 is connected to the feed signal transmission line 5a of cable 5 via the abnormal detection terminal 10a.In the event that the replacement of cable 5 is completed after the processing unit 20 has switched off the TRIAC 13 (if cable 5 is interrupted), a reset terminal 18 is provided to return the processing unit 20 to an initial state. Performing a reset operation at the reset terminal 18 returns the processing unit 20 to its initial state and switches the TRIAC 13 back on (resetting it to an unswitched-off state).

[0039] In the second conversion unit 30, two terminals (a positive terminal (+) 30b and a negative terminal (-) 30c) located below the connection terminals to the cable 5 define a second input section. These terminals are connected to one input side of the isolation transformer 31. Two terminals located below the connection terminals to the power tool 70, connected to both ends of the electrolytic capacitor C3, define a second output section. The electrolytic capacitor C2 is positioned between the two terminals that form the second input section. The isolation transformer 31, the switching element 32, the diodes D2 and D3, and the electrolytic capacitor C3 form a transformer circuit. The switching element 32 is located on the primary side of the isolation transformer 31. The diodes D2 and D3 are located on the secondary side of the isolation transformer 31. A voltage on the secondary side of the isolation transformer 31 is smoothed by the electrolytic capacitor C3.A voltage value (third voltage value) of a DC voltage on the secondary side of the isolation transformer 31 is, for example, 0 V or more and less than 400 V, and is particularly desirable to be set in the range of 0 V or more and less than 70 V to correspond to a rated voltage of the power tool 70 to be connected. The third voltage value is lower than the second voltage value. A sensing resistor R3 is provided in a path of an output current of the isolation transformer 31 and the electrolytic capacitor C3 (an output current of the second conversion unit 30). A current sensing circuit 35 detects the output current of the isolation transformer 31 and the electrolytic capacitor C3 based on a voltage across the sensing resistor R3. A voltage sensing circuit 34 detects a voltage across the isolation transformer 31.A switching control circuit 33 controls the switching on and off of the switching element 32 according to a current sensing value from the current sensing circuit 35 and a voltage sensing value from the voltage sensing circuit 34.

[0040] An auxiliary power supply 36 converts an input voltage from cable 5 into an operating voltage for the switching control circuit 33 and a processing unit 40 or similar. A temperature sensing circuit 38 contains a temperature sensing element, e.g., a thermistor, detects a temperature in the second conversion unit 30, and forwards it to the processing unit 40. The processing unit 40 is an example of a second control unit and contains a microcontroller. The processing unit 40 controls the second cooling fan 37 according to a temperature sensing value from the temperature sensing circuit 38. If an abnormal temperature is detected by the temperature sensing circuit 38, the processing unit 40 also sends an off signal (abnormality detection signal) to a processing unit 73 of the power tool 70 via an LD connection and stops the drive of the power tool 70.Resistors R4 and R5 are connected in series between a power supply line, to which an output voltage from the auxiliary power supply 36 is applied, and ground. A gate of switching element Q3 is connected to a connection terminal of resistors R4 and R5. A source of switching element Q3 is connected to ground. A drain of switching element Q3 is connected via an abnormality detection terminal 30a to the feed signal transmission line 5a of cable 5. Resistors R4 and R5 and switching element Q3 form a feed signal generator.

[0041] If cable 5 is not open, the voltage between the gate and source of switching element Q3 is positive, and switching element Q3 is switched on. Therefore, the abnormal detection terminals 30a and 10a are at ground potential. In the case where abnormal detection terminal 10a is at ground potential (when a feed signal is present from the feed signal transmission line 5a), the processing unit 20 determines that cable 5 is not open. If cable 5 is open, the voltage at abnormal detection terminal 10a is pulled up to 5 V by resistor R2.In the event that the voltage of the abnormality detection terminal 10a becomes 5 V when a DC voltage is output from the first conversion unit 10 to cable 5 (when the feed signal from the feed signal transmission line 5a disappears), the computing unit 20 determines that cable 5 has been interrupted, switches off the TRIAC 13 and interrupts the output of the first conversion unit 10.Furthermore, the cable 5 has a three-core structure which, in addition to the feed signal transmission line 5a, includes a plus(+)-side power supply line 5b, which connects the plus(+) terminal 10b provided on an output side of the first conversion unit 10 and the plus(+) terminal 30b provided on an input side of the second conversion unit 30, and a minus(-)-side power supply line 5c, which connects the minus(-) terminal 10c provided on the output side of the first conversion unit 10 and the minus(-) terminal 30c provided on the input side of the second conversion unit 30, and in some cases at least one of the plus(+)-side power supply line 5b and the minus(-)-side power supply line 5c is interrupted, and the feed signal transmission line 5a is not interrupted.Since in this case the output voltage of the auxiliary power supply 36 disappears, the voltage between the gate and the source of the switching element Q3 becomes 0, the switching element Q3 is switched off, and thus the voltage of the anomaly detection terminal 10a is pulled up to 5 V by the resistor R2.

[0042] The power tool 70 includes the trip switch 71, an inverter circuit 72, the control unit 73, a motor 74, and an electrolytic capacitor C4. The electrolytic capacitor C4 is connected between the input terminals of the inverter circuit 72. The inverter circuit 72 contains a switching element, such as a three-phase, bridge-connected FET or IGBT. The control unit 73 controls the drive of the motor 74 by controlling the inverter circuit 72. When the control unit 73 receives the off signal (anomaly detection signal) from the control unit 40 of the second conversion unit 30 via the LD terminal, it switches off the inverter circuit 72, regardless of the state of the trip switch 71, and stops the drive of the motor 74.

[0043] Fig. Figure 7 is a diagram showing an example of the relationship between the output current and output voltage of the second conversion unit 30 and the relationship between the output current and output voltage of the battery pack 80. The dashed line shows the current-voltage characteristic of the output of the battery pack 80. The solid line shows the current-voltage characteristic of the output of the second conversion unit 30. The battery pack 80 has the property that its output voltage decreases with increasing load current. Accordingly, the second conversion unit 30 also controls the output voltage using the switching control circuit 33, so that the second conversion unit 30 has a similar characteristic to the current-voltage characteristic of the output of the battery pack 80.That is, according to the current sensing value (load current value) from the current sensing circuit 35 and the voltage sensing value from the voltage sensing circuit 34, the switching control circuit 33 controls the switching element 32 so that the relationship between the voltage value and the current value is as shown by the solid line in . Fig. Figure 7 is shown. In order to suppress excessive current supply to the power tool 70, a constant current control is also carried out when the load current reaches 80 A, i.e., an example of the maximum output current of the second conversion unit 30, so that no further current is supplied.

[0044] According to the present embodiment, the following effects can be achieved. (1) Since in the first conversion unit 10 an input AC voltage is converted into a DC voltage which is higher than a peak value of the input AC voltage and is output to the cable 5, the current flowing through the cable 5 can be reduced and the power loss on the cable 5 suppressed, compared to the case in which the input AC voltage is converted into a DC voltage with a low voltage value and is output to the cable 5. (2) Since the first conversion unit 10 is configured to switch off the TRIAC 13 and interrupt the output of a DC voltage to the cable 5 when the cable 5 is interrupted, in the event that the cable 5 is accidentally cut by a circular saw or the like, it is possible to suppress the occurrence of a high DC voltage in the interrupted section of the cable 5. (3) By providing a large and heavy circuit component such as the power factor correction circuit 12 in the first conversion unit 10, the second conversion unit 30, which is connected to the power tool 70, can be made small and light, and the operability of the power tool 70 is good. (4) Since the output current-output voltage characteristic of the second conversion unit 30 is made similar to the output current-output voltage characteristic of the battery pack 80, the usability of the power tool 70 when supplied with power from the DC power supply device 1 can be approached to the usability of the power tool 70 when supplied with power from the battery pack 80. (5) The first conversion unit 10 has a protection function whereby the processing unit 20 switches off the TRIAC 13 and stops the output if an anomaly such as high temperature or overcurrent occurs. In addition, the second conversion unit 30 has a protection function whereby, upon the occurrence of an anomaly such as high temperature, the processing unit 40 sends an off signal to the power tool 70 via the LD terminal, and the processing unit 73 in the power tool 70, which has received the off signal, stops the drive of the power tool 70. In this way, both the first conversion unit 10 and the second conversion unit 30 have a protection function.By implementing the double protection as a whole, even in the case where, for example, a significant temperature increase occurs in only one of the first conversion unit 10 and the second conversion unit 30, the power supply of the power tool 70 or the drive of the power tool 70 can be stopped, and a malfunction of the DC power supply device 1 can be suppressed.

[0045] (Version 2) Fig. Figure 8 is a circuit block view of a DC power supply device 2 and the power tool 70 according to embodiment 2 of the present invention. Compared to the one in Fig.In embodiment 1 shown in Figure 6, the DC power supply device 2 differs in that a discharge resistor 23, a switching element Q2, and an AND gate 21 are added, and is otherwise identical. The discharge resistor 23 and the switching element Q2 are connected in series between the two terminals of the electrolytic capacitor C1, so that they are in parallel with the electrolytic capacitor C1. One gate of the switching element Q2 is connected to an output terminal of the AND gate 21. One input terminal of the AND gate 21 is connected to the other end of resistor R2 and the arithmetic unit 20. The other input terminal of the AND gate 21 is connected to a control terminal of the TRIAC 13 and the arithmetic unit 20.

[0046] If cable 5 is not interrupted and the output voltage of the first conversion unit 10 is normal (e.g., 380 V), then, because the switching element Q3 of the second conversion unit 30 is switched on, an input signal (signal from one input terminal of the AND gate 21) from the abnormal detection terminal 10a to the arithmetic unit 20 becomes 0 (low level). At this time, a gate signal (signal from the other input terminal of the AND gate 21) from the arithmetic unit 20 to the TRIAC 13 is also 0. Thus, the output of the AND gate 21 becomes 0, and the switching element Q2 is switched off.

[0047] When cable 5 is interrupted, and switching element Q3 is switched off, the input signal (signal from one input terminal of the AND circuit 21) from the abnormal detection terminal 10a to the processing unit 20 becomes 1 (high level), and the gate signal (signal from the other input terminal of the AND circuit 21) from the processing unit 20, which detects the interruption of the TRIAC 13, also becomes 1. Thus, the output of the AND circuit 21 becomes 1, and switching element Q2 is switched on. Consequently, the electrical charge of the electrolytic capacitor C1 is discharged via the discharge resistor 23 and the switching element Q2. Description of the reference numbers

[0048] 1, 2: DC power supply; 3: AC power supply; 5: Cable; 10: First conversion unit; 11: Power cord; 12: Power factor correction circuit; 13: TRIAC; 14: Diode bridge; 15: Auxiliary power supply; 16: Current sensing circuit; 17: First fan; 18: Reset terminal; 19: Temperature sensing circuit; 20: Arithmetic unit (first control unit); 21: AND gate; 22: Driver circuit; 23: Discharge resistor; 25: Boost and smoothing circuit; 26: Input terminal; 27: Exhaust terminal; 30: Second conversion unit; 31: Isolation transformer; 32: Switching element; 33: Switching control circuit; 34: Voltage sensing circuit; 35: Current sensing circuit; 36: Auxiliary power supply; 37: Second blower; 38: Temperature sensing circuit; 40: Processing unit (second control unit); 70: Power tool; 71: Trigger switch; 72: Inverter circuit; 73: Processing unit; 74: Motor; 75: Battery pack connection; 80: Battery pack

Claims

A DC power supply device (1, 2) comprising: a first conversion unit (10) connected to an external AC power supply (3); a second conversion unit (30) connected to an external power tool (70); and a cable (5) connecting the first conversion unit (10) and the second conversion unit (30), wherein the first conversion unit (10) comprises a power factor correction circuit (12), converts an AC voltage of a first voltage value input from the external AC power supply (3) into a DC voltage of a second voltage value higher than the first voltage value, and outputs the DC voltage of the second voltage value to the cable (5);The second conversion unit (30) converts an output voltage of the first conversion unit (10) input via the cable (5) into a DC voltage with a third voltage value that is lower than the second voltage value, and outputs the DC voltage with the third voltage value to the external power tool (70); the first conversion unit (10) includes a cut-off circuit (13) which cuts off the output of the DC voltage to the cable (5) when the cable (5) is interrupted; the first conversion unit (10) includes a first cooling fan (17) that generates cooling air within the first conversion unit (10); the second conversion unit (30) includes a second cooling fan (37) that generates cooling air within the second conversion unit (30); the first voltage value is 80 V or more and less than 260 V, the second voltage value is 200 V or more and less than 500 V, and the third voltage value is 0 V or more and less than 70 V V is; DC power supply device (1, 2) according to claim 1, wherein the second conversion unit (30) can be connected to a battery pack connection part (75) of the external power tool (70) instead of a battery pack (8), which is powered by the energy of the detachably connected battery pack (8). DC power supply device (1, 2) according to claim 1 or 2, wherein the second conversion unit (30) comprises a feed signal generator which generates a feed signal indicating that a DC voltage is supplied to the second conversion unit (30) via the cable; the cable (5) comprises a feed signal transmission line (5a) which transmits the feed signal from the second conversion unit (30) to the first conversion unit (10); the shutdown circuit (13) shuts off the output of the DC voltage to the cable (5) when the feed signal disappears from the feed signal transmission line while the DC voltage is being output to the cable (5). DC power supply device (1, 2) according to claim 3, wherein the first conversion unit (10) comprises a first control part (20) which is connected to the feed signal transmission line (5a) and controls the shutdown circuit (13). DC power supply device (1, 2) according to claim 4, wherein the first control part (20) sets the shutdown circuit (13) to a shutdown state when an abnormality is detected. DC power supply device (1, 2) according to claim 5, wherein the second conversion unit (30) comprises a second control unit (40), and the second control unit (40) sends an abnormality detection signal to the external power tool (70) connected thereto when the abnormality is detected. DC power supply device (1, 2) according to one of claims 4 to 6, wherein the first conversion unit (10) comprises a reset terminal (18) which resets the first control unit (20) to an initial state, and the first control unit (20) puts the shutdown circuit (13) into a non-shutdown state when it is reset to the initial state. DC power supply device (1, 2) according to one of claims 3 to 7, wherein the shutdown circuit (13) comprises a switching element (32) which is provided in a path of an alternating current of the first conversion unit (10). DC power supply device (1, 2) according to one of the preceding claims, wherein the first conversion unit (10) comprises a first control part (20) that controls the drive of the first cooling fan (17); the second conversion unit (30) comprises a second control part (40) that controls the drive of the second cooling fan (37). DC power supply device (1, 2) according to one of claims 1 to 9, wherein the second conversion unit (30) reduces an output voltage thereof when an output current thereof increases. DC power supply device (1, 2) according to any one of claims 1 to 10, wherein the first conversion unit (10) comprises: a first input part connected to the external AC power supply (3) into which the AC voltage of the first voltage value is input; the power factor correction circuit (12) connected to the first input part; a rectifier circuit (14) connected to an output side of the power factor correction circuit (12); a boost circuit (25) that amplifies an output voltage of the rectifier circuit (14); a smoothing circuit (25) that smooths an output voltage of the boost circuit (25); and a first output part (10b and 10c) that is connected to the cable (5) and outputs the DC voltage of the second voltage value output by the smoothing circuit (25) to the cable (5). DC power supply device (1, 2) according to one of claims 1 to 11, wherein the second conversion unit (30) comprises: a second input part (30b and 30c) connected to the cable (5), into which the DC voltage of the second voltage value is input; a transformer circuit that transforms the DC voltage input into the second input part and outputs the DC voltage of the third voltage value, which is lower than the second voltage value; and a second output part that is connected to the external power tool (70) and outputs a voltage from the transformer circuit to the external power tool (70). DC power supply device (1, 2) according to claim 12, wherein the transformer circuit comprises an isolation transformer (31) and a switching element (32) connected to a primary side of the isolation transformer. A DC power supply device (1, 2) comprising: a first conversion unit (10) connected to an external AC power supply (3); a second conversion unit (30) connected to an external power tool (70); and a cable (5) connecting the first conversion unit (10) and the second conversion unit (30), wherein the first conversion unit (10) comprises a power factor correction circuit (12), converts an AC voltage of a first voltage value input from the external AC power supply (3) into a DC voltage of a second voltage value higher than the first voltage value, and outputs the DC voltage of the second voltage value to the cable (5);the second conversion unit (30) converts an output voltage of the first conversion unit (10), which is input via the cable (5), into a DC voltage of a third voltage value, which is lower than the second voltage value, and outputs the DC voltage of the third voltage value to the external power tool (70); the first conversion unit (10) includes a shutdown circuit (13) which, when an abnormality is detected, shuts off an output of the DC voltage to the cable (5); the first conversion unit (10) includes a first cooling fan (17) which generates cooling air inside the first conversion unit (10);the second conversion unit (30) comprises a second cooling fan (37) which generates cooling air within the second conversion unit (30), the first voltage value being 80 V or more and less than 260 V, the second voltage value being 200 V or more and less than 500 V, and the third voltage value being 0 V or more and less than 70 V. DC power supply device (1, 2) according to claim 1, wherein the first cooling fan (17) is provided at a rear end and within the first conversion unit (10), the first conversion unit (10) comprising: a first input port (26) provided at a front part of the first conversion unit (10); and a first exhaust port (27) provided at a rear part of the first conversion unit (10), wherein the cable (5) is connected to a front end of the first conversion unit (10). DC power supply device (1, 2) according to claim 15, wherein the first conversion unit (10) comprises an electrolytic capacitor (C1) and a rectifier circuit (14) arranged between the first input terminal (26) and the first exhaust terminal (27) in a front-to-back direction of the DC power supply device (1, 2). DC power supply device (1, 2) according to claim 1, wherein the second cooling fan (37) is provided at a rear end and within the second conversion unit (30), the second conversion unit (30) comprising: second inlet openings provided on both side faces of the second conversion unit (30); and a second outlet opening provided on a rear part of the second conversion unit (30). The DC power supply device (1, 2) according to claim 17, wherein the second conversion unit (30) comprises: an isolation transformer (31); and two fins (41, 42) arranged on both sides of the isolation transformer (31) to guide the cooling air drawn in through the second inlet openings. The DC power supply device (1, 2) according to claim 1 further comprises: a power cable (11) arranged between the first conversion unit (10) and an external AC power supply (3), wherein the length of the cable (5) is greater than the length of the power cable (11).

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