Energy supply control unit

Abstract

Power supply control device (10) with a switching unit (31) configured to switch on and off a first semiconductor switch (20) and a second semiconductor switch (30) whose current input contact is connected to a current output contact of the first semiconductor switch (20), wherein the power supply control device (10) is configured to control a supply of electrical energy via the second semiconductor switch (30) by switching with the switching unit (31), wherein the first semiconductor switch (20) and the second semiconductor switch (30) are switched off when a voltage at a control contact is at least at a switch-on threshold value, and the first semiconductor switch (20) and the second semiconductor switch (30) are switched off when the voltage at the control contact is below a switch-off threshold value, the energy supply control device (10) comprises: a resistor (R1) connected between a current input contact and the control contact of the first semiconductor switch (20); and a diode (D2) whose cathode is connected to the control contact of the first semiconductor switch (20) and whose anode is connected to the control contact of the second semiconductor switch (30), wherein the switching unit (31) performs the switching by adjusting a voltage at the control contact of the second semiconductor switch (30), characterized in that the energy supply control device (10) further comprises the following: a parasitic diode (Dp1) whose cathode and anode are connected to the current output contact and the current input contact of the first semiconductor switch (20); and a capacitor (C1) that is connected between the control contact of the first semiconductor switch (20) and the current output contact of the second semiconductor switch (30).

Description

TECHNICAL AREA

[0001] The present invention relates to a power supply control device which is configured to control the supply of electrical energy via a switch. TECHNICAL BACKGROUND

[0002] An example of a power supply control device designed to control the supply of electrical power to a load from a vehicle battery is a power supply control device in which the drain and source of an N-channel FET (field-effect transistor) are each connected to a positive electrode of the battery and one end of the load, and a negative electrode of the battery is connected to the other end of the load. The FET acts as a semiconductor switch for the power supply control device. The FET is turned on by raising the voltage at the gate to at least a turn-on threshold and turned off by lowering the voltage at the gate below a turn-off threshold. When the FET is turned on, the load receives electrical power from the battery, and when the FET is turned off, the supply of electrical power to the load from the battery is stopped.

[0003] However, a parasitic diode is formed between the drain and source of the FET. The cathode and anode of the parasitic diode are each connected to the drain and source of the N-channel FET, respectively. If the positive and negative electrodes of the battery are incorrectly connected to the other end of the load and the drain of the FET, current will flow continuously from the other end of the load to the first end, even when the FET is switched off. This poses a risk of the load malfunctioning.

[0004] JP 5 772 776 B2 discloses a power supply control device capable of preventing current flow when its battery is incorrectly connected. The power supply control device disclosed in this patent document comprises two N-channel FETs (field-effect transistors), with the drain of one FET connected to the drain of the other. A positive electrode of the battery is connected to the source of one FET, and one end of the load is connected to the source of the other FET. A negative electrode of the battery is connected to the other end of the load. The supply of electrical energy to the load from the battery is controlled by simultaneously switching both FETs on and off.

[0005] The cathode of the parasitic diode in one of the FETs is connected to the cathode of the parasitic diode in the other FET. Therefore, when both FETs are switched off, no current flows from the battery to the load, regardless of the battery connection status.

[0006] The generic patent JP 2006-158 185 A discloses a power semiconductor device comprising a first field-effect transistor of the metal-insulating-film semiconductor type and a second field-effect transistor of the metal-insulating-film semiconductor type, arranged in multiple series circuits between a negative electrode terminal and the source region of a power semiconductor switching element of a cascode element, wherein a high-speed diode is electrically connected in parallel to the cascode element. The power semiconductor switching element is of the self-conducting type, and the first field-effect transistor of the metal-insulating-film semiconductor type and the second field-effect transistor of the metal-insulating-film semiconductor type are of the self-blocking type.

[0007] German patent DE 10 2010 015 096 A1 discloses a driver circuit for a load, comprising a first power transistor as a high-side switch for the load and a second power transistor designed as an NMOS transistor as a battery protection switch. The load path of the first power transistor and the load path of the second power transistor are connected in series between a first terminal of a voltage source and the load, and a first terminal of the load path and the bulk terminal of the second power transistor are connected to the first terminal of the voltage source. The load path of a bipolar transistor is provided between the gate terminal and the first terminal of the second power transistor, with the base terminal of the bipolar transistor connected to a capacitor that is charged when the second power transistor is switched on. OVERVIEW OF THE INVENTION TASKS TO BE SOLVED BY THE INVENTION

[0008] As disclosed in JP 5 772 776 B2, a power supply control device with two N-channel FETs is conceivable, configured to switch two FETs on and off via a drive circuit. In such a power supply control device, for example, the gates of the two FETs are directly connected to an output contact of the drive circuit. The drive circuit increases the voltage output at the output contact, thereby increasing the gate voltages of the two FETs from zero V and switching the two FETs on. Furthermore, the drive circuit decreases the voltage output at the output contact, thereby reducing the gate voltages of the two FETs to zero V and switching the two FETs off.

[0009] As described above, the power supply control device, in which the output contact of the driver circuit is directly connected to the gates of the two FETs, has a single driver circuit and can therefore be manufactured cost-effectively. However, in this power supply control device, the two FETs must be switched on and off using a driver circuit, which means that switching each FET on and off takes a considerable amount of time, and such a power supply control device is problematic because it has a high switching loss.

[0010] The present invention arose in light of the aforementioned circumstances, and its objective is to provide a cost-effective energy supply control device with low switching losses. MEANS OF SOLVING THE TASK

[0011] A power supply control device according to the present invention is a power supply control device having the features of one of claims 1, 2 and 4.

[0012] According to one aspect of the present invention, the current output contact of the first semiconductor switch is connected to the current input contact of the second semiconductor switch, and the resistor is connected between the current input contact and the control contact of the first semiconductor switch. The cathode and anode of the diode are connected to the control contacts of the first and second semiconductor switches, respectively. For example, the positive electrode of the battery is connected to the current input contact of the first semiconductor switch, one end of the load is connected to the current output contact of the second semiconductor switch, and the negative electrode of the battery is connected to the other end of the load.

[0013] If the voltage at the control contact of the second semiconductor switch falls below the voltage supplied by the battery, no current flows from the positive electrode of the battery through the resistor, and the voltage at the control contact of the first semiconductor switch is maintained at the voltage supplied by the battery. The switching unit then activates the first and second semiconductor switches, thereby energizing parasitic capacitors connected to the control contacts of both switches and increasing the voltage at the control contact of the second semiconductor switch.

[0014] While the voltage at the control contact of the second semiconductor switch is below the voltage supplied by the battery, the switching unit only supplies current to the parasitic capacitance connected to the control contact of the second semiconductor switch, thereby increasing the voltage at that contact. When the voltage at the control contact of the second semiconductor switch is at least equal to the voltage supplied by the battery, the switching unit supplies current to the parasitic capacitances connected to the control contacts of both the first and second semiconductor switches, thereby increasing the voltage at both contacts. This switches on both the first and second semiconductor switches.Since the voltage at the control contact of the first semiconductor switch is held at the voltage supplied by the battery beforehand, the first semiconductor switch and the second semiconductor switch are switched on in a short time and exhibit a low switching loss.

[0015] For example, by connecting the control contact of the second semiconductor switch to the negative electrode of the battery via an internal resistor, the switching unit discharges the parasitic capacitances associated with the control contacts of the second semiconductor switch, reduces the voltage across these contacts, and switches the second semiconductor switch off. Conversely, when the control contact of the second semiconductor switch is connected to the negative electrode of the battery, the parasitic capacitance associated with the control contact of the first semiconductor switch discharges through the resistor, the voltage across the control contact of the first semiconductor switch drops, and the first semiconductor switch is switched off.Since the parasitic capacitance connected to the control contact of the first semiconductor switch discharges through the resistance, it is sufficient for the switching unit to only discharge the parasitic capacitance connected to the control contact of the second semiconductor switch. Thus, the first and second semiconductor switches are switched off quickly and exhibit low switching losses.

[0016] The first semiconductor switch and the second semiconductor switch are switched on and off by adjusting the voltage at the control contact of the second semiconductor switch and can therefore be manufactured cost-effectively.

[0017] The power supply control device according to one aspect of the present invention comprises a parasitic diode, the cathode and anode of which are connected to the current output contact and the current input contact of the first semiconductor switch, and a capacitor which is connected between the control contact of the first semiconductor switch and the current output contact of the second semiconductor switch.

[0018] When the positive electrode of the battery is connected to the current input contact of the first semiconductor switch, one end of the load is connected to the current output contact of the second semiconductor switch, and the negative electrode of the battery is connected to the other end of the load, then, according to one aspect of the present invention, the capacitor is charged by the battery when the first and second semiconductor switches are off. When the switching unit increases the voltage at the control contact of the second semiconductor switch, the current flowing through the second semiconductor switch to the load increases, and the voltage at the current output contact of the second semiconductor switch also increases.Even if the voltage at the control contact of the second semiconductor switch is lower than the voltage supplied by the battery, the voltage at one end of the capacitor on the battery side exceeds the battery's output voltage, and the parasitic capacitance connected to the control contact of the first semiconductor switch is charged. As a result, the first semiconductor switch turns on faster.

[0019] In the power supply control device according to one aspect of the present invention, the number of second semiconductor switches and the number of diodes are each at least two and equal, the current input contacts of several of the second semiconductor switches are connected to the current output contact of the first semiconductor switch, cathodes of several of the diodes are connected to the control contact of the first semiconductor switch, anodes of the several diodes are each connected to the control contacts of the several second semiconductor switches, and the switching unit adjusts voltages at the control contacts of the several second semiconductor switches individually.

[0020] According to one aspect of the present invention, the current input contacts of several second semiconductor switches are connected to the current output contact of the first semiconductor switch. The cathodes of the several diodes are connected to the control contact of the first semiconductor switch, and the anodes of the several diodes are each connected to the control contacts of the several second semiconductor switches. When the switching unit increases the voltage at at least one of the control contacts of the several second semiconductor switches, the first semiconductor switch, a second semiconductor switch with the increased voltage at its control contact, or one or more second semiconductor switches corresponding to the several control contacts are switched on. The power supply via the several second semiconductor switches is controlled by individually switching the several second semiconductor switches on and off.

[0021] The power supply control device according to one aspect of the present invention comprises a parasitic diode, the cathode and anode of which are connected to the current output contact and the current input contact of the first semiconductor switch, several second diodes, the cathodes of which are connected to the control contact of the first semiconductor switch, several third diodes, the cathodes of which are each connected to anodes of the several second diodes and the anodes of which are connected to the current output contact of the first semiconductor switch, and several capacitors, each of which has one end connected to the anodes of the several second diodes, wherein the number of second diodes, the number of third diodes and the number of capacitors is the same as the number of second semiconductor switches and the other ends of the several capacitors are each connected to current output contacts of the several second semiconductor switches.

[0022] When the positive electrode of the battery is connected to the current input contact of the first semiconductor switch, one end of the load is connected to the current output contacts of the second semiconductor switches, and the negative electrode of the battery is connected to the other end of the load, according to one aspect of the present invention, the multiple capacitors are each charged via the third diodes when the first semiconductor switch and the second semiconductor switches are off. When the switching unit increases the voltage at the control contact of a second semiconductor switch while the first semiconductor switch and the second semiconductor switches are off, the voltage at the current output contact of the second semiconductor switch increases.Even if the voltage at the control contact of the second semiconductor switch is lower than the voltage supplied by the battery, the voltage at one end on the battery side of a capacitor, one end of which is connected to the current output contact of the second semiconductor switch, exceeds the voltage supplied by the battery, and the parasitic capacitance connected to the control contact of the first semiconductor switch is charged via the second diode. Consequently, the first semiconductor switch is turned on faster.

[0023] In the power supply control device according to one aspect of the present invention, the first semiconductor switch is turned on and off depending on the voltage at the control contact with respect to a potential of the current input contact, and the second semiconductor switch is turned on and off depending on the voltage at the control contact with respect to a potential of the current output contact.

[0024] According to one aspect of the present invention, the first semiconductor switch and the second semiconductor switches are, for example, N-channel FETs, and the drain of the first semiconductor switch is connected to the drains of the second semiconductor switches.

[0025] The power supply control device according to one aspect of the present invention comprises a switch which is connected between the current input contact and the control contact of the first semiconductor switch and is turned on when a voltage negative with respect to the potential of the current output contact of the several second semiconductor switches is applied to the current input contact of the first semiconductor switch, wherein the first semiconductor switch is turned off when a voltage between the current input contact and the control contact is approximately zero V.

[0026] According to one aspect of the present invention, when a negative voltage, relative to the potential of the current output contact of the second semiconductor switch, is applied to the current input contact of the first semiconductor switch, the switch turns on, the voltage between the current input contact and the control contact of the first semiconductor switch becomes approximately zero V, and the first semiconductor switch turns off. Thus, even when the first semiconductor switch and the second semiconductor switches are turned on, the first semiconductor switch is forced to turn off when a negative voltage, relative to the potential of the current output contact of either of the second semiconductor switches, is applied to the current input contact of the first semiconductor switch. Therefore, current flow from the second semiconductor switches to the first semiconductor switch is reliably prevented. EFFECT OF INVENTION

[0027] According to the present invention, the power supply control device can be manufactured cost-effectively with low switching losses. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram showing the design of the main sections of a power supply system according to embodiment 1. Fig. Figure 2 is a circuit diagram of a power supply control device. Fig. Figure 3 is a time sequence diagram to illustrate the switching on of a second semiconductor switch. Fig. Figure 4 is a circuit diagram of a power supply control device according to embodiment 2. Fig. Figure 5 is a time sequence diagram to illustrate the effect of a capacitor. Fig. Figure 6 is a block diagram showing the design of the main sections of a power supply system according to embodiment 3. Fig. Figure 7 is a circuit diagram of a power supply control device. Fig. Figure 8 is a circuit diagram of a control circuit. FORMS OF EXECUTION OF THE INVENTION

[0028] The present invention is described in detail below with reference to the drawings, which show embodiments. Design 1

[0029] Fig. Figure 1 is a block diagram showing the configuration of the main sections of a power supply system 1 according to embodiment 1. The power supply system 1 is expediently installed in a vehicle and comprises a power supply control unit 10, a battery 11, a conductor 12, and a load A1. The conductor 12 is, for example, the vehicle body.

[0030] The power supply control unit 10 is separately connected to conductor 12, one end of load A1, and a positive electrode contact T1. The other end of load A1 and a negative electrode contact T2 are also connected to conductor 12. Battery 11 is disconnectably connected between positive electrode contact T1 and negative electrode contact T2. A normal connection state of battery 11 is one in which the positive electrode of battery 11 is connected to positive electrode contact T1 and the negative electrode of battery 11 is connected to negative electrode contact T2. A faulty connection state of battery 11 is one in which the positive electrode of battery 11 is connected to negative electrode contact T2 and the negative electrode of battery 11 is connected to positive electrode contact T1.

[0031] When battery 11 is properly connected, it supplies electrical energy to load A1 via the power supply control unit 10. The power supply control unit 10 controls the supply of electrical energy to load A1 from battery 11. Load A1 is an electrical device installed in the vehicle; when the load is supplied with electrical energy, it is operational, and when the power supply is interrupted, the load ceases operation.

[0032] If the battery 11 is incorrectly connected, the power supply control unit 10 prevents current from flowing from the negative electrode contact T2 to the load A1.

[0033] Fig. Figure 2 is a circuit diagram of the power supply control unit 10. The power supply control unit 10 has a first semiconductor switch 20, a switch 21, a microcontroller 22, a control circuit B1, a diode D1 and resistors R1, R2 and R3.

[0034] The first semiconductor switch 20 is an N-channel FET. Therefore, the power supply control device 10 further comprises a parasitic diode Dp1 and parasitic capacitors Cs1 and Cd1, which are formed during the fabrication of the first semiconductor switch 20. The parasitic diode Dp1 is connected between the drain and the source of the first semiconductor switch 20, and the cathode and anode of the parasitic diode Dp1 are connected to the drain and source, respectively, of the first semiconductor switch 20. The parasitic capacitor Cs1 is connected between the gate and the source of the first semiconductor switch 20, and the parasitic capacitor Cd1 is connected between the gate and the drain of the first semiconductor switch 20. The switch 21 is an NPN bipolar transistor.

[0035] The control circuit B1 has a second semiconductor switch 30, a control unit 31 and a diode D2.

[0036] The second semiconductor switch 30 is an N-channel FET. Therefore, the control circuit B1 further comprises a parasitic diode Dp2 and parasitic capacitors Cs2 and Cd2, which are formed during the fabrication of the second semiconductor switch 30. The parasitic diode Dp2 is connected between the drain and the source of the second semiconductor switch 30, and the cathode and anode of the parasitic diode Dp2 are connected to the drain and source, respectively, of the second semiconductor switch 30. The parasitic capacitor Cs2 is connected between the gate and the source of the second semiconductor switch 30, and the parasitic capacitor Cd2 is connected between the gate and the drain of the second semiconductor switch 30.

[0037] The source of the first semiconductor switch 20 is connected to the positive electrode contact T1. The drain of the first semiconductor switch 20 is connected to the drain of the second semiconductor switch 30 of the control circuit B1. The source of the second semiconductor switch 30 is connected to one end of the load A1. The gate of the first semiconductor switch 20 is connected to the cathode of diode D2 of the control circuit B1. The anode of diode D2 is connected to the gate of the second semiconductor switch 30. The control unit 31 is also connected to the gate of the second semiconductor switch 30. The microcontroller 22 is also connected to the control unit 31.

[0038] An emitter of switch 21 and one end of each resistor R1 and R2 are individually connected to the source of the first semiconductor switch 20. A collector of switch 21 and the other end of resistor R1 are connected to the gate of the first semiconductor switch 20. In this way, switch 21 and resistor R1 are connected between the source and the gate of the first semiconductor switch 20.

[0039] The other end of resistor R2 is connected to the base of switch 21 and one end of the third resistor R3. The other end of resistor R3 is connected to the cathode of diode D1. The anode of diode D1 is connected to conductor 12.

[0040] When the voltage at the gate of the first semiconductor switch 20, relative to the source potential, is at least at a turn-on threshold value Vn1, the resistance between the source and the drain is approximately zero Ω. At this point, the first semiconductor switch 20 is turned on. When the voltage at the gate of the first semiconductor switch 20, relative to the source potential, falls below a turn-off threshold value Vf1, the resistance between the source and the drain is sufficiently high that hardly any current flows between the source and the drain. Therefore, when the voltage at the gate of the first semiconductor switch 20, relative to the source potential, is below the turn-off threshold value Vf1, the first semiconductor switch 20 is turned off. The turn-off threshold value Vf1 is positive and is less than the turn-on threshold value Vn1.

[0041] When the voltage at the gate of the second semiconductor switch 30 reaches at least a turn-on threshold value Vn2 with respect to the potential of the source, the resistance between the source and the drain is approximately zero Ω. At this point, the second semiconductor switch 30 is turned on. When the voltage at the gate of the second semiconductor switch 30 falls below a turn-off threshold value Vf2 with respect to the potential of the source, the resistance between the source and the drain is sufficiently high that hardly any current flows between the source and the drain. Thus, when the voltage at the gate of the second semiconductor switch 30 falls below the turn-off threshold value Vf2 with respect to the potential of the source, the second semiconductor switch 30 is turned off. The turn-off threshold value Vf2 is positive and is less than the turn-on threshold value Vn2.

[0042] When the voltage at the base of switch 21, relative to the emitter potential, reaches at least a turn-on threshold Vn3, the resistance between the emitter and collector is approximately Ω. At this point, switch 21 is turned on. When the voltage at the base of switch 21, relative to the emitter potential, falls below a turn-off threshold Vf3, the resistance between the emitter and collector is sufficiently high that hardly any current flows between them. Therefore, when the voltage at the gate of switch 21, relative to the emitter potential, falls below the turn-off threshold Vf3, switch 21 is turned off. The turn-off threshold Vf3 is positive and is lower than the turn-on threshold Vn3.

[0043] When battery 11 is normally connected, no current flows through resistors R2 and R3 due to the action of diode D1. Therefore, the voltage at the base of switch 21 with respect to the emitter potential is approximately zero V and is less than the turn-off threshold Vf3. Thus, when battery 11 is normally connected, switch 21 is off.

[0044] If battery 11 is incorrectly connected, in other words, if a negative voltage relative to the potential of the source of the second semiconductor switch 30 in control circuit B1 is applied to the source of the first semiconductor switch 20, a current flows from the negative electrode contact T2 through conductor 12, diode D1, resistors R3 and R2 to the positive electrode contact T1, in that order. During this process, the voltage across resistor R2 decreases, and the voltage at the base of switch 21 relative to the emitter potential rises to at least the turn-on threshold Vn3, and switch 21 is turned on. When switch 21 is turned on, the voltage at the gate of the first semiconductor switch 20 relative to the source potential is approximately zero V, and the voltage is below the turn-off threshold Vf1. At this point, the first semiconductor switch 20 is off.

[0045] Therefore, if battery 11 is incorrectly connected, switch 21 will be turned on, and the first semiconductor switch 20 will be turned off. Since, as described above, the cathode of the parasitic diode Dp1 is connected to the drain of the first semiconductor switch 20, no current flows from the drain to the source of the first semiconductor switch 20 when the first semiconductor switch 20 is off. Therefore, if battery 11 is incorrectly connected, no current flows to load A1.

[0046] If the battery 11 is incorrectly connected while the first semiconductor switch 20 is off, no current flows from the negative electrode contact T2 to the load A1, regardless of whether the switch 21 is on.

[0047] Even if the first semiconductor switch 20 and the second semiconductor switch 30 are switched on, a faulty connection of the battery 11 forces the first semiconductor switch 20 to be switched off, thus reliably preventing current from flowing to the load A1.

[0048] The following describes the power supply control unit 10 under normal connection conditions of the battery 11. For the sake of simplicity, the voltage drop across each of the parasitic diodes Dp1 and Dp2 and diode D2 in the forward direction is considered sufficiently small.

[0049] In the first semiconductor switch 20, current is supplied from the gate to the parasitic capacitances Cs1 and Cd1, and the voltage at the gate with respect to the potential of the source is increased to at least the turn-on threshold Vn1. This turns on the first semiconductor switch 20.

[0050] Furthermore, discharging the parasitic capacitances Cs1 and Cd1 reduces the gate voltage below the turn-off threshold Vf1 relative to the source potential. This turns off the first semiconductor switch 20.

[0051] In the second semiconductor switch 30, current is supplied from the gate to the parasitic capacitances Cs2 and Cd2, and the voltage at the gate with respect to the potential of the source is increased to at least the turn-on threshold Vn2. This turns on the second semiconductor switch 30.

[0052] Furthermore, discharging the parasitic capacitances Cs2 and Cd2 reduces the gate voltage below the turn-off threshold Vf2 relative to the source potential. This turns off the second semiconductor switch 30.

[0053] The microcontroller 22 feeds a control signal to instruct the control of load A1 and a stop signal to instruct the control of load A1 to stop into the control unit 31 of the control circuit B1.

[0054] When the control signal is applied, the control unit 31 outputs a control voltage higher than the voltage Vb supplied by battery 11 via an internal resistor (not shown) to the gate of the second semiconductor switch 30 and the gate of the first semiconductor switch 20. The control unit 31 outputs the control voltage via the internal resistor and diode D2 to the gate of the first semiconductor switch 20.

[0055] The control unit 31 outputs the control voltage, which supplies current to the parasitic capacitances Cs2 and Cd2 from the gate of the second semiconductor switch 30 and to the parasitic capacitances Cs1 and Cd1 from the gate of the first semiconductor switch 20. This charges the parasitic capacitances Cs1, Cd1, Cs2, and Cd2, and the voltages at the gates of the first semiconductor switch 20 and the second semiconductor switch 30 increase with respect to the potentials of their sources.

[0056] The control unit 31 outputs the control voltage, causing the voltage at the gate of the first semiconductor switch 20 to reach at least the turn-on threshold Vn1 with respect to the source potential, and the voltage at the gate of the second semiconductor switch 30 to reach at least the turn-on threshold Vn2 with respect to the source potential. This turns on the first semiconductor switch 20 and the second semiconductor switch 30.

[0057] When the second semiconductor switch 30 is switched on, current flows from the positive electrode contact T1 to the source and drain of the first semiconductor switch 20 and to the drain and source of the second semiconductor switch 30, in that order.

[0058] The source of the first semiconductor switch 20 and the drain of the second semiconductor switch 30 thus serve as current input contacts, and the drain of the first semiconductor switch 20 and the source of the second semiconductor switch 30 serve as current output contacts. The gates of the first semiconductor switch 20 and the second semiconductor switch 30 serve as control contacts.

[0059] When the control unit 31 receives a stop signal from the microcontroller 22, it connects the gate of the second semiconductor switch 30 to conductor 12 via its internal resistance. Consequently, current flows from the parasitic capacitances Cs2 and Cd2 to the control unit 31, discharging the parasitic capacitances Cs2 and Cd2. The voltage at the gate of the second semiconductor switch 30 falls below the turn-off threshold Vf2, and the second semiconductor switch 30 is turned off. When the second semiconductor switch 30 is turned off, the power supply to load A1 ceases, and the operation of load A1 ends.

[0060] When the discharge ends in a state where the gate of the second semiconductor switch 30 is connected to the conductor 12, the voltage at the drain of the second semiconductor switch 30 is approximately equal to the voltage Vb output by the battery 11, and the voltages at the gate and source of the second semiconductor switch 30 are approximately zero V.

[0061] When the microcontroller 22 outputs the stop signal to the control unit 31, and the control unit 31 connects the gate of the second semiconductor switch 30 to conductor 12, the voltage output from the control unit 31 to the gate of the first semiconductor switch 20 ceases. Therefore, current flows from one end of the parasitic capacitances Cs1 and Cd1 on the gate side of the first semiconductor switch 20 through resistor R1, and the parasitic capacitances Cs1 and Cd1 of the first semiconductor switch 20 discharge. Consequently, the voltage at the gate of the first semiconductor switch 20 falls below the turn-off threshold Vf1 with respect to the source potential, and the first semiconductor switch 20 is turned off.

[0062] The microcontroller 22 controls the operation of the control circuit B1 by outputting the control signal or the stop signal to the control unit 31.

[0063] When the parasitic capacitances Cs1 and Cd1 terminate the discharge in a state in which the gate of the second semiconductor switch 30 is connected to the conductor 12 via the internal resistance of the drive unit 31, the voltages between the two ends of the parasitic capacitances Cs1 and Cd1 are approximately zero V, and the electrical energy accumulated in the parasitic capacitances Cs1 and Cd1 is approximately zero W.

[0064] When the control unit 31 outputs the control voltage across its internal resistance as described above and connects the gate of the second semiconductor switch 30 to conductor 12 via its internal resistance, it adjusts the voltage at the gate of the second semiconductor switch 30 and switches the first semiconductor switch 20 and the second semiconductor switch 30 on and off. This controls the supply of electrical energy to the load A1 via the second semiconductor switch 30. The control unit 31 acts as a switching unit.

[0065] In the power supply control unit 10, the control unit 31 switches the first semiconductor switch 20 and the second semiconductor switch 30 from off to on at high speed.

[0066] A comparative example of a power supply control device is one in which resistor R1 is omitted and the gate of the first semiconductor switch 20 is connected to the gate of the second semiconductor switch 30 without diode D2 in between. The control unit 31 outputs the control voltage, enabling the power supply control device, as in the comparative example, to switch the first semiconductor switch 20 and the second semiconductor switch 30 from off to on.

[0067] In this case, the control units 31 supply the same electrical energy or power to the energy supply control unit 10 and the energy supply control unit according to the comparison example.

[0068] Fig. Figure 3 is a time sequence diagram to illustrate the switching on of the second semiconductor switch 30. Fig. Figure 3 shows a change in the source voltage Vs2 and a change in the gate voltage Vg2 at the second semiconductor switch 30. Hereafter, the source voltage Vs2 and the gate voltage Vg2 are referred to as the source voltage Vs2 and the gate voltage Vg2, respectively. The source voltage Vs2 and the gate voltage Vg2 are each voltages with respect to the potential of conductor 12. The change in the gate voltage Vg2 and the change in the source voltage Vs2 are indicated by thick and thin lines, respectively. A section where the change in the gate voltage Vg2 and the change in the source voltage Vs2 overlap is indicated by a thick line.

[0069] In the case of the power supply control unit 10 and the power supply control unit according to the comparison example, the direction of change of the source voltage Vs2 and the direction of change of the gate voltage Vg2 do not differ.

[0070] Below, the period from the start of the control voltage output by the control unit 31 until the gate voltage Vg2 reaches the switch-off threshold Vf2 is referred to as the first period, and the period from the point at which the gate voltage reaches the switch-off threshold Vf2 until the source voltage Vs2 reaches the voltage Vb output by battery 11 is referred to as the second period. Furthermore, the period from the point at which the source voltage Vs2 reaches the voltage Vb output by battery 11 until the gate voltage Vg2 reaches the control voltage is referred to as the third period. The first and second periods are shorter for the power supply control unit 10 than the first and second periods for the supply control unit according to the comparative example.The length of the third period is approximately equal to the length of the third period in the energy supply control unit 10 according to the comparison example.

[0071] First, the switching on of the power supply control device according to the comparative example is described. When the first semiconductor switch 20 and the second semiconductor switch 30 are switched off in the power supply control device according to the comparative example, current flows from the positive electrode contact T1 through the parasitic capacitance Cs1 to the control unit 31, in that order, and current flows from the positive electrode contact T1 through the parasitic diode Dp1 and the parasitic capacitance Cd1 to the control unit 31, in that order. The voltages at the source and drain of the first semiconductor switch 20 with respect to the gate potential thus correspond approximately to the voltage Vb output by the battery 11. Therefore, the voltages at the gate of the first semiconductor switch 20 are negative with respect to the source and drain potentials.

[0072] In the first period, the parasitic capacitances Cs1 and Cs2 are charged. Current is supplied to parasitic capacitance Cs1 from the gate of the first semiconductor switch (20V), and current is supplied to parasitic capacitance Cs2 from the gate of the second semiconductor switch (30V). The gate voltage Vg2 increases due to the charging of parasitic capacitance Cs2. The source voltage Vs2 is held at zero until a difference between the gate voltage Vg2 and the source voltage Vs2 reaches the turn-off threshold Vf2.

[0073] When the difference between the gate voltage Vg2 and the source voltage Vs2 reaches the turn-off threshold Vf2, current flows between the drain and the source of the second semiconductor switch 30. Since the first semiconductor switch 20 is off at this time, current flows from the positive electrode contact T1 through the parasitic diode Dp1 of the first semiconductor switch 20.

[0074] When current flows to load A1, a voltage is generated between both ends of load A1, and the source voltage Vs2 increases. The voltage between both ends of load A1 also increases along with the increase in current flowing to load A1. During the second period, the parasitic capacitances Cs1, Cd1, and Cd2 are charged. The gate voltage Vg2 increases due to the charging of the parasitic capacitance Cd2. Current is supplied to the parasitic capacitances Cs1 and Cd1 from the gate of the first semiconductor switch 20. Current is supplied to the parasitic capacitance Cd2 from the gate of the second semiconductor switch 30.

[0075] As the gate voltage Vg2 increases, the current flowing to load A1 increases, and the source voltage Vs2 rises. The source voltage Vs2 rises along with the increase in the gate voltage Vg2 until it reaches the voltage Vb supplied by battery 11, while the difference between the source voltage Vs2 and the gate voltage Vg2 is maintained at the turn-off threshold Vf2. After reaching the voltage Vb supplied by battery 11, the source voltage Vs2 is held at this voltage.

[0076] In the third period, the parasitic capacitances Cs1, Cd1, Cs2, and Cd2 are charged. As Cs2 and Cd2 charge, the gate voltage Vg2 rises to the control voltage, while the source voltage Vs2 is maintained at the voltage Vb supplied by battery 11. When the difference between the gate voltage Vg2 and the source voltage Vs2 is at least equal to the turn-on threshold Vn2, the second semiconductor switch 30 of the control circuit B1 is turned on.

[0077] The voltage at the gate of the first semiconductor switch 20 with respect to the potential of conductor 12 changes in the same way as the gate voltage Vg2, and the voltage at the source of the first semiconductor switch 20 with respect to the potential of conductor 12 is approximately equal to the voltage Vb supplied by the battery 11. The voltage at the gate of the first semiconductor switch 20 with respect to the source potential increases from a negative voltage. When the voltage at the gate with respect to the source potential reaches at least the turn-on threshold Vn1, the first semiconductor switch 20 is turned on.

[0078] Next, the switching on of the power supply control device 10 is described. When the first semiconductor switch 20 and the second semiconductor switch 30 of the power supply control device 10 are switched off, the parasitic capacitance Cs1 discharges through resistor R1, and the parasitic capacitance Cd1 discharges through resistor R1 and diode Dp1. Therefore, the voltage at the gate of the first semiconductor switch 20 with respect to the voltage at the source and the voltage at the gate with respect to the voltage at the drain are approximately zero V. The voltage at the gate of the first semiconductor switch 20 with respect to the potential of conductor 12 is approximately equal to the voltage Vb output by battery 11.

[0079] During the first period, from the time when the control unit 31 starts outputting the control voltage until the time when the gate voltage Vg2 of the second semiconductor switch 30 reaches the voltage Vb output by the battery 11, no voltage is output by the control unit 31 to the gate of the first semiconductor switch 20.

[0080] In the first period, all the electrical energy supplied by the control unit 31 is directed to the parasitic capacitance Cs2, and only the parasitic capacitance Cs2 is charged. The parasitic capacitance Cs2 is energized by the gate of the second semiconductor switch 30. The gate voltage Vg2 increases as the parasitic capacitance Cs2 charges. The source voltage Vs2 is held at zero V until the difference between the gate voltage Vg2 and the source voltage Vs2 reaches the turn-off threshold Vf2. The turn-off threshold Vf2 is lower than the voltage Vb supplied by the battery 11.

[0081] When the difference between the gate voltage Vg2 and the source voltage Vs2 reaches the turn-off threshold Vf2, current flows between the drain and the source of the second semiconductor switch 30. Since the first semiconductor switch 20 is off at this time, current flows from the positive electrode contact T1 through the parasitic diode Dp1 of the first semiconductor switch 20.

[0082] During the first period, the voltage at the drain of the first semiconductor switch 20 increases due to a rise in the gate voltage Vg2. The voltage at the gate of the first semiconductor switch 20, however, is maintained at the voltage Vb supplied by the battery 11. In this way, the parasitic capacitance Cd1 is charged. However, the electrostatic capacitance of the parasitic capacitance Cd1 is, for example, one-tenth of the electrostatic capacitance of the parasitic capacitance Cs1 and is therefore sufficiently small that the electrical energy supplied to the parasitic capacitance Cd1 during the first period is negligible.

[0083] When current flows to load A1, a voltage is generated between both ends of load A1, and the source voltage Vs2 increases. The voltage between both ends of load A1 also increases along with an increase in the current flowing to load A1. In the second period, the parasitic capacitance Cd2 is charged, and the gate voltage Vg2 increases. Current is supplied to the parasitic capacitance Cd2 from the gate of the second semiconductor switch 30.

[0084] In the power supply control unit 10, similar to the power supply control unit in the comparison example, the source voltage Vs2 increases along with an increase in the gate voltage Vg2 until it reaches the voltage Vb output by battery 11, while the difference between the source voltage Vs2 and the gate voltage Vg2 is maintained at the turn-off threshold Vf2. After reaching the voltage Vb output by battery 11, the source voltage Vs2 is held at the voltage Vb output by battery 11.

[0085] In the third period, similar to the power supply control unit in the comparative example, the parasitic capacitances Cs1, Cd1, Cs2, and Cd2 are charged. As the parasitic capacitances Cs2 and Cd2 are charged, the gate voltage Vg2 rises to the control voltage, while the source voltage Vs2 is maintained at the voltage Vb supplied by battery 11. When the difference between the gate voltage Vg2 and the source voltage Vs2 reaches at least the turn-on threshold Vn2, the second semiconductor switch 30 of the control circuit Bk is turned on.

[0086] The voltage at the gate of the first semiconductor switch 20 with respect to the potential of conductor 12 is maintained at the voltage Vb supplied by battery 11, while the gate voltage Vg2 is below the voltage Vb supplied by battery 11. The voltage at the gate of the first semiconductor switch changes in the same way as the gate voltage Vg2 after the gate voltage Vg2 reaches at least the voltage Vb supplied by battery 11. The voltage at the source of the first semiconductor switch 20 with respect to the potential of conductor 12 is approximately equal to the voltage Vb supplied by battery 11. The voltage at the gate of the first semiconductor switch 20 with respect to the potential of the source increases from zero V. When the voltage at the gate with respect to the potential of the source reaches at least the turn-on threshold Vn1, the first semiconductor switch 20 is turned on.

[0087] As described above, in the power supply control device according to the comparative example, the control unit 31 outputs the control voltage, which charges the parasitic capacitances Cs1 and Cs2 in the first period, the parasitic capacitances Cs1, Cd1, and Cd2 in the second period, and the parasitic capacitances Cs1, Cd1, Cs2, and Cd2 in the third period. When the control unit 31 outputs the control voltage, the voltages at the gate of the first semiconductor switch 20 are negative with respect to the source and drain potentials. Therefore, the parasitic capacitance Cs1 is charged in the first period, and the parasitic capacitances Cs1 and Cd1 are charged in the second period.

[0088] In contrast, in the power supply control unit 10, when the control unit 31 outputs the control voltage, the parasitic capacitance Cs2 is charged in the first period, the parasitic capacitance Cd2 is charged in the second period, and the parasitic capacitances Cs1, Cd1, Cs2, and Cd2 are charged in the third period. When the control unit 31 outputs the control voltage, the voltage at the gate of the second semiconductor switch 30 is lower than the voltage Vb output by the battery 11. While the voltage at the gate of the second semiconductor switch 30 is lower than the voltage Vb output by the battery 11, the voltage at the gate of the first semiconductor switch 20 is held at the output voltage Vb, and the voltages at the source and drain potentials are zero V.Therefore, it is not necessary to charge the parasitic capacity Cs1 in the first period, and it is not necessary to charge the parasitic capacities Cs1 and Cd1 in the second period.

[0089] In the power supply control unit 10, therefore, little time elapses between the output of the control voltage by the control unit 31 and the switching on of the first semiconductor switch 20 and the second semiconductor switch 30. Thus, the power supply control unit 10 exhibits low switching losses caused by the switching of the first semiconductor switch 20 and the second semiconductor switch 30 from off to on. Furthermore, it does not take long for current to flow through the parasitic diode Dp1 of the first semiconductor switch 20, and the power consumption is low.

[0090] In the power supply control unit 10, the control unit 31 switches the first semiconductor switch 20 and the second semiconductor switch 30 from on to off at high speed.

[0091] When, in the power supply control device according to the comparative example, the control unit 31 connects the gate of the second semiconductor switch 30 to conductor 12 via its internal resistance, current flows from the parasitic capacitances Cs1, Cd1, Cs2, and Cd2 to the control unit 31, and the parasitic capacitances Cs1, Cd1, Cs2, and Cd2 discharge. If the voltage at the gate of the first semiconductor switch 20 falls below the turn-off threshold Vf1 with respect to the source potential, the first semiconductor switch 20 is turned off, as described above. If the voltage at the gate of the second semiconductor switch 30 falls below the turn-off threshold Vf2 with respect to the source potential, the second semiconductor switch 30 is turned off.

[0092] When the control unit 31 of the power supply control device 10 connects the gate of the second semiconductor switch 30 to conductor 12 via its internal resistance, current flows from the parasitic capacitances Cs2 and Cd2 to the control unit 31, and the parasitic capacitances Cs2 and Cd2 discharge. The parasitic capacitances Cs1 and Cd1 discharge via resistor R1. Therefore, little time elapses between the moment the control unit 31 connects the second semiconductor switch 30 to conductor 12 via its internal resistance and the moment the voltage at the gate of the second semiconductor switch 30 falls below the turn-off threshold Vf2 with respect to the source potential. Thus, the power supply control device 10 exhibits a low switching loss caused by the switching of the first semiconductor switch 20 and the second semiconductor switch 30 from on to off.

[0093] The first semiconductor switch 20 and the second semiconductor switch 30 are switched on and off by adjusting the voltage at the gate of the second semiconductor switch 30 by means of the control unit 31, which is why the power supply control device 10 can be manufactured cost-effectively. Design 2

[0094] Fig. Figure 4 is a circuit diagram of a power supply control device 10 according to embodiment 2.

[0095] The following describes embodiment 2 with regard to its differences from embodiment 1. All embodiments other than those described below are identical to those in embodiment 1; therefore, components identical to those in embodiment 1 are provided with the same reference numerals and their further description is omitted.

[0096] In the energy supply system 1 according to embodiment 2, an energy supply control device 10, a battery 11, a conductor 12 and a load A1 are connected in the same way as in embodiment 1.

[0097] A comparison of the power supply control unit 10 from embodiment 2 with the power supply control unit 10 from embodiment 1 shows that they differ in that the control circuit B1 additionally includes a capacitor C1. The capacitor C1 is connected between the gate of a first semiconductor switch 20 and the source of a second semiconductor switch 30. Therefore, when a control unit 31 outputs a control voltage to the gate of the second semiconductor switch 30, the first semiconductor switch 20 switches more quickly from off to on. A description of the power supply control unit 10 with the battery 11 connected normally follows.

[0098] Fig. Figure 5 is a time sequence diagram to illustrate the effect of capacitor C1. Analogous to Fig. 3 shows Fig. 5. The gate voltage Vg2 and the source voltage Vs2 of the second semiconductor switch 30 are shown using thick and thin lines. When the control unit 31 of the power supply control device 10 from embodiment 2 begins to output the control voltage, the gate voltage Vg2 and the source voltage Vs2 also change in the same way as in embodiment 1.

[0099] Fig. Figure 5 further shows a change in the source voltage Vs1 and a change in the gate voltage Vg1 at the first semiconductor switch 20. Hereinafter, the source voltage Vs1 is referred to as the source voltage Vs1 and the gate voltage Vg1 as the gate voltage Vg1. The source voltage Vs1 and the gate voltage Vg1 are each voltages with respect to the potential of conductor 12. The change in the gate voltage Vg1 and the change in the source voltage Vs1 are indicated by thick and thin lines, respectively. A section where the change in the gate voltage Vg1 and the change in the source voltage Vs1 overlap is indicated by a thick line.

[0100] When the second semiconductor switch 30 is off, current flows from a positive electrode contact T1 to a resistor R1 and the capacitor C1 in that order, and the capacitor C1 is charged. The capacitor C1 is charged until the voltage between its two ends is approximately equal to the voltage Vb supplied by battery 11. When the control unit 31 supplies the control voltage, the voltage between its two ends is approximately equal to the voltage Vb supplied by battery 11.

[0101] If, as in Fig. As shown in Figure 5, if the gate voltage Vg2 is below the voltage Vb supplied by battery 11 and the source voltage Vs2 is approximately zero V, the gate voltage Vg1 and the source voltage Vs1 are each kept at the voltage Vb supplied by battery 11.

[0102] As described in embodiment 1, in a second period the source voltage Vs2, i.e., a voltage at one end of capacitor C1 on the side of load A1, increases along with an increase in the gate voltage Vg2. Since at this point the voltage between both ends of capacitor C1 is approximately equal to the voltage Vb output by battery 11, the voltage at one end of capacitor C1 on the side of resistor R1 exceeds the voltage Vb output by battery 11. Current is supplied from capacitor C1 to the parasitic capacitances Cd1 and Cs1 of the first semiconductor switch 20, and the parasitic capacitances Cd1 and Cs1 are charged. In this way, the gate voltage Vg2 is lower than the voltage Vb output by battery 11, but the gate voltage Vg1 increases along with the increase in gate voltage Vg2.

[0103] The source voltage Vs1 of the first semiconductor switch 20 is maintained at the voltage Vb supplied by the battery 11. When the difference between the gate voltage Vg1 and the source voltage Vs1 is at least equal to a turn-on threshold Vn1, the first semiconductor switch 20 is turned on. Subsequently, the gate voltage Vg1 is maintained at the control voltage supplied by the control unit 31 and stabilizes.

[0104] As described above, in the power supply control device 10 of embodiment 2, the time between the output of the control voltage by the control unit 31 and the switching on of the first semiconductor switch 20 is shorter. Since the first semiconductor switch 20 is switched on more quickly in this way, the period in which current flows through a parasitic diode Dp 1 in the first semiconductor switch 20 is even shorter, and the power consumption of the first semiconductor switch 20 is even lower.

[0105] When the first semiconductor switch 20 and the second semiconductor switch 30 are switched on, the source voltage Vs2 of the second semiconductor switch 30 corresponds approximately to the voltage Vb output by the battery 11, and the gate voltage Vg1 of the first semiconductor switch 20 corresponds approximately to the control voltage output by the control unit 31.

[0106] Furthermore, since the capacitor C1 is connected between the gate of the first semiconductor switch 20 and the source of the second semiconductor switch 30, the first semiconductor switch 20 is switched from on to off more quickly when the control unit 31 connects the gate of the second semiconductor switch 30 to the conductor 12 via its internal resistance.

[0107] When the control unit 31 connects the gate of the second semiconductor switch 30 to the conductor 12 via its internal resistance, as described in embodiment 1, the parasitic capacitances Cd2 and Cs2 discharge and the gate voltage Vg2 of the second semiconductor switch 30 decreases. Correspondingly, the resistance between the drain and the source of the second semiconductor switch 30 increases, the current flowing to a load A1 decreases, and the source voltage Vg2 of the second semiconductor switch 30 decreases. A voltage across one end of capacitor C1 on the side of resistor R1 also decreases, along with a decrease in the source voltage Vs2.

[0108] When the control unit 31 connects the gate of the second semiconductor switch 30 to the conductor 12 via its internal resistance, the parasitic capacitances Cd1 and Cs1 discharge through the resistor R1 in the same way as in embodiment 1. In the power supply control unit 10 from embodiment 2, the voltage at one end of the capacitor C1 on the side of the resistor R1 also drops, which is why current also flows from the parasitic capacitances Cd1 and Cs1 to the capacitor C1. Accordingly, the parasitic capacitances Cd1 and Cs1 discharge, and the capacitor C1 is charged.

[0109] Therefore, the parasitic capacitances Cd1 and Cs1 discharge through the resistor R1 and charge the capacitor C1, which is why the voltage at the gate of the first semiconductor switch 20 drops faster and the first semiconductor switch 20 switches from on to off faster.

[0110] The energy supply control device 10 from embodiment 2 has all the components of the energy supply control device 10 from embodiment 1 and therefore has similar effects to the energy supply control device 10 from embodiment 1. embodiment 3

[0111] In embodiment 2, the number of loads whose electrical energy supply is controlled by the power supply control unit 10 is one. However, the number of loads whose electrical energy supply is controlled by the power supply control unit 10 can also be two or more.

[0112] The following describes embodiment 3 with regard to its differences from embodiment 2. All embodiments other than those described below are identical to those in embodiment 2; therefore, components identical to those in embodiment 2 are provided with the same reference numerals and their further description is omitted.

[0113] Fig. Figure 6 is a block diagram showing the configuration of the main sections of a power supply system 1 from embodiment 3. Similar to embodiment 2, a power supply system 1 from embodiment 3 has a power supply control unit 10, a battery 11, a conductor 12, and a load A1. These are connected in the same way as in embodiment 2. The power supply system 1 from embodiment 3 also has (n - 1) loads A2, A3, ... and An (where n is an integer of at least two). One end of each of the loads A2, A3, ... and An is connected to the power supply control unit 10, and the other end of each of the loads A2, A3, ... and An is connected to the conductor 12.

[0114] When battery 11 is normally connected, electrical energy is supplied separately from battery 11 to loads A1, A2, ... and An via the power supply control unit 10. The power supply control unit 10 controls the supply of electrical energy from battery 11 to loads A1, A2, ... and An. Like load A1, loads A2, A3, ... and An are electrical devices installed in the vehicle. When these loads are supplied with electrical energy, they are operational, and when the power supply is interrupted, they cease to operate.

[0115] If the battery 11 is incorrectly connected, the power supply control unit 10 prevents current from flowing from the negative electrode contact T2 to the n loads A1, A2, ... and An.

[0116] Fig. Figure 7 is a circuit diagram of the power supply control unit 10. In the same manner as the power supply control unit 10 from embodiment 2, the power supply control unit 10 from embodiment 3 comprises a first semiconductor switch 20, a switch 21, a microcontroller 22, a control circuit B1, parasitic capacitors Cd1 and Cs1, a parasitic diode Dp1, a diode D1, and resistors R1, R2, and R3. These are connected in the same way as in embodiment 2.

[0117] The power supply control unit 10 of embodiment 3 further comprises (n - 1) control circuits B2, B3, ... and Bn. The control circuits B2, B3, ... and Bn are each connected to the gate and drain of the first semiconductor switch 20 and the microcontroller 22. The control circuits B2, B3, ... and Bn are also connected to one end of each of the n loads A2, A3, ... and An.

[0118] Fig.Figure 8 is a circuit diagram of a control circuit Bk (k = 1, 2, ... and n). In a similar manner to the control circuit B1 from embodiment 2, the control circuit Bk in embodiment 3 has the second semiconductor switch 30, the control unit 31, the parasitic capacitances Cs2 and Cd2, the capacitor C1, the parasitic diode Dp2 and the diode D2.

[0119] The second semiconductor switch 30, the control unit 31, the parasitic capacitors Cs2 and Cd2, the parasitic diode Dp2 and the diode D2 are connected in the same way as in embodiment 2, except for the connection of the source of the second semiconductor switch 30.

[0120] Thus, the drain of the second semiconductor switch 30 of the control circuit Bk is connected to the drain of the first semiconductor switch 20. Furthermore, the cathode of diode D2 of the control circuit Bk is connected to the gate of the first semiconductor switch 20, and the anode of diode D2 of the control circuit Bk is connected to the gate of the second semiconductor switch 30 of the control circuit Bk.

[0121] The source of the second semiconductor switch 30 of the control circuit Bk is connected to one end of the load Ak.

[0122] The control circuit Bk further comprises diodes D3 and D4. In the control circuit Bk, the cathode of diode D3 is connected to the gate of the first semiconductor switch 20. The anode of diode D3 is connected to the cathode of diode D4 and one end of capacitor C1. The anode of diode D4 is connected to the drain of the first semiconductor switch 20. The other end of capacitor C1 is connected to the source of the second semiconductor switch 30. Similar to the forward voltage drop across each of the parasitic diodes Dp1 and Dp2 and diode D2, the forward voltage drop across each of diodes D3 and D4 is also considered sufficiently small.

[0123] As described above, the power supply control device 10 of embodiment 3 has the n control circuits B1, B2, ... and Bn, and the control circuit Bk (k = 1, 2, ... and n) has the second semiconductor switch 30, the capacitor C1 and the diodes D2, D3 and D4. The number of second semiconductor switches 30, the number of capacitors C1, the number of diodes D2, the number of diodes D3 and the number of diodes D4 of the power supply control device 10 are therefore each n and are equal.

[0124] Diode D3 serves as a second diode and diode D4 serves as a third diode.

[0125] A control signal to instruct the control of a load Ak and a stop signal to instruct the stopping of the control of the load Ak are fed by the microcontroller 22 into the control unit 31 of the control circuit Bk (k = 1, 2, ... and n).

[0126] When the control signal is applied, the control unit 31 of the control circuit Bk, similar to the control unit 31 from embodiment 2, outputs a control voltage via its internal resistance (not shown) to the gate of the second semiconductor switch 30 of the control circuit Bk and the gate of the first semiconductor switch 20. Accordingly, voltages rise at the gates of the first semiconductor switch 20 and the second semiconductor switch 30 of the control circuit Bk, and the first semiconductor switch 20 and the second semiconductor switch 30 of the control circuit Bk are switched on.

[0127] When the second semiconductor switch 30 of the control circuit Bk is switched on, current flows from the positive electrode contact T1 to the source and drain of the first semiconductor switch 20 and to the drain and source of the second semiconductor switch 30 of the control circuit Bk, in that order. When the first semiconductor switch 20 and the second semiconductor switch 30 of the control circuit Bk are switched on, the load Ak is supplied with electrical energy, and the load Ak is in operation.

[0128] When the control unit 31 of the control circuit Bk receives the stop signal, it connects the gate of the second semiconductor switch 30 of the control circuit Bk to the conductor 12 via its internal resistance in the same way as the control unit 31 from embodiment 2. Accordingly, the parasitic capacitances Cs2 and Cd2 of the control circuit Bk discharge, the voltage at the gate of the second semiconductor switch 30 of the control circuit Bk falls below the turn-off threshold Vf2, and the second semiconductor switch 30 is turned off. Therefore, the supply of electrical energy to the load Ak ends, and the operation of the load Ak ceases.

[0129] The microcontroller 22 controls the operation of the n control circuits B1, B2, ... and Bn separately by outputting the control signal or the stop signal to the control units 31 of the n control circuits B1, B2, ... and Bn.

[0130] When the microcontroller 22 outputs the stop signal to the control units 31 of the n control circuits B1, B2, ... and Bn, and the control units 31 of all n control circuits B1, B2, ... and Bn connect the gates of the second semiconductor switches 30 to conductor 12, the output of voltages to the gate of the first semiconductor switch 20 ceases. In this case, the parasitic capacitances Cs1 and Cd1 discharge through resistor R1. Accordingly, the voltage at the gate of the first semiconductor switch 20 falls below the turn-off threshold Vf1 with respect to the source potential, and the first semiconductor switch 20 is turned off.

[0131] As described above, the control units 31 of the n control circuits B1, B2, ... and Bn individually adjust the voltages at the gates of the n second semiconductor switches 30 and switch the n second semiconductor switches 30 on and off. In this way, the supply of electrical energy to the loads A1, A2, ... and An is controlled via the n second semiconductor switches 30. In embodiment 3, the n control units 31 serve as switching units.

[0132] If at least one of the n control units 31 outputs the control voltage, that is, if at least one of the n second semiconductor switches 30 is switched on, the first semiconductor switch 20 is switched on. If all n control units 31 connect the gates of the second semiconductor switches 30 to the conductor 12 via their internal resistance, that is, if all n second semiconductor switches 30 are switched off, the first semiconductor switch 20 is switched off.

[0133] When the multiple second semiconductor switches 30 are switched on and one of the gates of the switched-on multiple second semiconductor switches 30 is connected to conductor 12 via the internal resistance of the control unit 31, the parasitic capacitances Cs1 and Cd1 do not discharge due to the effect of diode D2. Therefore, even if one of the control units 31 connects the gate of the second semiconductor switch 30 to conductor 12 via its internal resistance, only the second semiconductor switch 30 connected to conductor 12 via its internal resistance is switched off, as long as at least one of the other control units 31 outputs the control voltage.

[0134] When the control unit 31 of the control circuit Bk outputs the control voltage while the first semiconductor switch 20 and the n second semiconductor switches 30 are switched off, the first semiconductor switch 20 is switched on faster due to the effect of the capacitor C1, similar to embodiment 2.

[0135] When the second semiconductor switch 30 of the control circuit Bk is off, current flows from the positive electrode contact T1 via the parasitic diode Dp1 and the diode D4 to capacitor C1 when the first semiconductor switch 20 is off, and capacitor C1 is charged. Similarly, when the first semiconductor switch 20 is on, current flows from the positive electrode contact T1 via the first semiconductor switch 20 and the diode D4 to capacitor C1, and capacitor C1 is charged. When the second semiconductor switch 30 of the control circuit Bk is off, capacitor C1 is charged until the voltage between its two ends is approximately equal to the voltage Vb supplied by battery 11, regardless of whether the first semiconductor switch 20 is on.

[0136] The following is a description of the operating processes of the power supply control device 10 when the control unit 31 of the control circuit Bk outputs the control voltage while the first semiconductor switch 20 and the n second semiconductor switches 30 are switched off. If the voltage at the gate of the second semiconductor switch 30 is lower than the voltage Vb output by the battery 11 and the voltage at the source of the second semiconductor switch 30 is approximately zero V, the voltages at the gate and at the source of the first semiconductor switch 20 are maintained at the voltage Vb output by the battery 11 in the same manner as in embodiment 2.

[0137] In the second period, during which the voltage at the source of the second semiconductor switch 30 increases along with the voltage at the gate of the second semiconductor switch 30, the voltage between both ends of capacitor C1 approximately corresponds to the voltage Vb supplied by battery 11, similar to embodiment 2. Therefore, the voltage at one end of capacitor C1 on the side of resistor R1 exceeds the voltage Vb supplied by battery 11. Accordingly, current is supplied from capacitor C1 to the parasitic capacitances Cd1 and Cs1 of the first semiconductor switch 20 via diode D3, and the parasitic capacitances Cd1 and Cs1 are charged. In this way, the gate voltage Vg2 is lower than the voltage Vb supplied by battery 11, but the gate voltage Vg1 increases along with the increase in the gate voltage Vg2.

[0138] The voltage at the source of the first semiconductor switch 20 is maintained at the voltage Vb supplied by the battery 11. When the difference between the gate voltage Vg1 and the source voltage Vs1 of the first semiconductor switch 20 is at least equal to the turn-on threshold Vn1, the first semiconductor switch 20 is turned on. Subsequently, the gate voltage Vg1 is maintained at the voltage Vb supplied by the battery 11 and stabilizes.

[0139] As described above, in the power supply control device 10 of embodiment 3, the time between the output of the control voltage by the control unit 31 and the switching on of the first semiconductor switch 20 is shorter. Since the first semiconductor switch 20 is switched on more quickly in this way, the period in which current flows through the parasitic diode Dp1 of the first semiconductor switch 20 is even shorter, and the power consumption of the first semiconductor switch 20 is even lower.

[0140] In embodiment 3, diode D3, like diode D2, prevents the first semiconductor switch 20 from being switched off simultaneously with the switching off of one of the several switched-on second semiconductor switches 30. When, in the control circuit Bk, the control unit 31 stops outputting the control voltage and connects the gate of the second semiconductor switch 30 to the conductor 12 via its internal resistance, the parasitic capacitances Cs2 and Cd2 discharge in the same manner as in embodiment 2, and the voltage at the gate of the second semiconductor switch 30 drops. Correspondingly, the current flowing through the load Ak decreases, which is why the voltage at the source of the second semiconductor switch 30, i.e., the voltage between the two ends of the load Ak, also drops.

[0141] When the voltage at the source of the second semiconductor switch 30 drops, the voltage at one end of capacitor C1 on the side of resistor R1 also drops. However, the control circuit Bk is equipped with diode D3, which prevents current from flowing from the parasitic capacitances Cs1 and Cd1 to capacitor C1. Thus, even if one of the n control units 31 stops outputting the control voltage and connects the gate of the second semiconductor switch 30 to conductor 12 via its internal resistance, the first semiconductor switch 20 remains switched on as long as at least one of the other control units 31 is outputting the control voltage. Therefore, if several of the n loads A1, A2, ... and An are operating and the operation of one of the loads is terminated, the operation of any other operating load will not be unexpectedly terminated.

[0142] In embodiment 3, the power supply control unit 10 has resistor R1, and the control circuit Bk (k = 1, 2, ... and n) has diode D2. Therefore, the first semiconductor switch 20 and the second semiconductor switches 30 are switched on and off within a short time in the same manner as in embodiments 1 and 2, resulting in low switching losses for this power supply control unit 10. Furthermore, the n control units 31 switch the first semiconductor switch and the n second semiconductor switches 30 on and off by individually adjusting the voltages at the gates of the n second semiconductor switches 30. Therefore, the power supply control unit 10 can be manufactured cost-effectively. In addition, if the battery 11 is incorrectly connected, the first semiconductor switch 20 is switched off, reliably preventing current from flowing from the negative electrode contact T2 to the n loads A1, A2, ... and An.

[0143] It should be noted that in embodiments 1 to 3, it is sufficient if the switch 21 is turned on from the off state when the battery 11 is incorrectly connected, and therefore it is not limited to an NPN bipolar transistor, but can also be, for example, a PNP bipolar transistor or a FET.

[0144] The disclosed embodiments 1 to 3 are to be considered exemplary in every respect and in no way limiting. The scope of the present invention is defined by the scope of the appended claims and not by the description above, and all modifications within the scope defined by the claims are also included. REFERENCE MARK LIST 10 Energy supply control unit 20 first semiconductor switch 21 switches 30 second semiconductor switch 31 Control unit (section of the switching unit) C1 Capacitor Dp1 parasitic diode D2 diode D3 Diode (second diode) D4 Diode (third diode) R1 resistor

Claims

[1] Power supply control device (10) with a switching unit (31) configured to switch on and off a first semiconductor switch (20) and a second semiconductor switch (30) whose current input contact is connected to a current output contact of the first semiconductor switch (20), wherein the power supply control device (10) is configured to control a supply of electrical energy via the second semiconductor switch (30) by switching with the switching unit (31), wherein the first semiconductor switch (20) and the second semiconductor switch (30) are switched off when a voltage at a control contact is at least at a switch-on threshold value, and the first semiconductor switch (20) and the second semiconductor switch (30) are switched off when the voltage at the control contact is below a switch-off threshold value, the energy supply control device (10) comprises: a resistor (R1) connected between a current input contact and the control contact of the first semiconductor switch (20); and a diode (D2) whose cathode is connected to the control contact of the first semiconductor switch (20) and whose anode is connected to the control contact of the second semiconductor switch (30), wherein the switching unit (31) performs the switching by adjusting a voltage at the control contact of the second semiconductor switch (30), characterized by , that the energy supply control device (10) further comprises the following: a parasitic diode (Dp1) whose cathode and anode are connected to the current output contact and the current input contact of the first semiconductor switch (20); and a capacitor (C1) that is connected between the control contact of the first semiconductor switch (20) and the current output contact of the second semiconductor switch (30). [2] Power supply control device (10) with a switching unit (31) configured to switch on and off a first semiconductor switch (20) and a second semiconductor switch (30) whose current input contact is connected to a current output contact of the first semiconductor switch (20), wherein the power supply control device (10) is configured to control a supply of electrical energy via the second semiconductor switch (30) by switching with the switching unit (31), wherein the first semiconductor switch (20) and the second semiconductor switch (30) are switched off when a voltage at a control contact is at least at a switch-on threshold value, and the first semiconductor switch (20) and the second semiconductor switch (30) are switched off when the voltage at the control contact is below a switch-off threshold value, the energy supply control device (10) comprises: a resistor (R1) connected between a current input contact and the control contact of the first semiconductor switch (20); and a diode (D2) whose cathode is connected to the control contact of the first semiconductor switch (20) and whose anode is connected to the control contact of the second semiconductor switch (30), wherein the switching unit (31) performs the switching by adjusting a voltage at the control contact of the second semiconductor switch (30), characterized by , that: the number of second semiconductor switches (30) and the number of diodes (D2) is each at least two and equal to the current input contacts of several of the second semiconductor switches (30) are connected to the current output contact of the first semiconductor switch (20), cathodes of several of the diodes (D2) are connected to the control contact of the first semiconductor switch (20), The anodes of the multiple diodes (D2) are each connected to the control contacts of the multiple second semiconductor switches (30), and the switching unit (31) individually adjusts the voltages at the control contacts of the several second semiconductor switches (30). [3] Energy supply control device (10) according to claim 2, further comprising: a parasitic diode (Dp1) whose cathode and anode are connected to the current output contact and the current input contact of the first semiconductor switch (20); several second diodes (D3) whose cathodes are connected to the control contact of the first semiconductor switch (20); several third diodes (D4), whose cathodes are each connected to the anodes of the several second diodes (D3) and whose anodes are connected to the current output contact of the first semiconductor switch (20); and several capacitors (C1), each having one end connected to the anodes of the several second diodes (D3), where the number of second diodes (D3), the number of third diodes (D4) and the number of capacitors (C1) is equal to the number of second semiconductor switches (30) and other ends of the multiple capacitors (C1) are each connected to the current output contacts of the multiple second semiconductor switches (30). [4] Power supply control device (10) with a switching unit (31) configured to switch on and off a first semiconductor switch (20) and a second semiconductor switch (30) whose current input contact is connected to a current output contact of the first semiconductor switch (20), wherein the power supply control device (10) is configured to control a supply of electrical energy via the second semiconductor switch (30) by switching with the switching unit (31), wherein the first semiconductor switch (20) and the second semiconductor switch (30) are switched off when a voltage at a control contact is at least at a switch-on threshold value, and the first semiconductor switch (20) and the second semiconductor switch (30) are switched off when the voltage at the control contact is below a switch-off threshold value, the energy supply control device (10) comprises: a resistor (R1) connected between a current input contact and the control contact of the first semiconductor switch (20); and a diode (D2) whose cathode is connected to the control contact of the first semiconductor switch (20) and whose anode is connected to the control contact of the second semiconductor switch (30), wherein the switching unit (31) performs the switching by adjusting a voltage at the control contact of the second semiconductor switch (30), wherein the first semiconductor switch (20) is switched on and off depending on the voltage at the control contact with respect to a potential of the current input contact and wherein the second semiconductor switch (30) is switched on and off depending on the voltage at the control contact with respect to a potential of the current input contact; characterized by, that the power supply control device (10) further comprises a switch (21) which is connected between the current input contact and the control contact of the first semiconductor switch (20) and is switched on when a voltage negative with respect to the potential of the current output contacts of the second semiconductor switch (30) is applied to the current input contact of the first semiconductor switch (20), wherein the first semiconductor switch (20) is switched off when the voltage between the current input contact and the control contact is approximately zero V.

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