JP6598252B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply apparatus including a main power supply unit that outputs a main drive voltage to a load, and a sub power supply unit that outputs a subdrive voltage to a load instead of the main power supply unit when the main drive voltage drops.

  Conventionally, in various fields, the main power supply unit that outputs the main drive voltage generated from commercial AC voltage to the load, and the sub drive voltage is applied to the load instead of the main power supply unit when the main drive voltage drops due to a power failure, etc. A power supply device including a sub power supply unit for outputting is used. Such a power supply is often called an “uninterruptible power supply”.

  As a conventional uninterruptible power supply, for example, there is a power supply 100 shown in FIG. The power supply apparatus 100 includes a main power supply unit 101, a sub power supply unit 102, and an electric double layer capacitor 103. The main power supply unit 101 includes a rectifying / smoothing circuit that converts commercial AC voltage into direct current, and a first DC / DC converter that converts the output voltage into a predetermined main drive voltage. Further, the sub power supply unit 102 includes a second DC / DC converter that converts the voltage of the electric double layer capacitor 103 into a predetermined sub drive voltage.

  The first DC / DC converter of the main power supply unit 101 outputs a main drive voltage to the load 104, the sub power supply unit 102, and the electric double layer capacitor 103. In addition, the second DC / DC converter of the sub power supply unit 102 uses the power stored in the electric double layer capacitor 103 when the main drive voltage decreases due to a power failure or the like, and supplies the sub drive voltage to the load 104. Output.

JP-A-6-351245

  In the conventional power supply device 100, the main power supply unit 101 and the sub power supply unit 102 are connected in parallel to the load 104. Therefore, in this power supply device 100, in order to prevent an overvoltage from being applied to the load 104, the output of the drive voltage (main drive voltage, sub drive voltage) is stopped in each of the main power supply unit 101 and the sub power supply unit 102. It was necessary to provide a switch for this purpose.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a power supply apparatus in which the number of parts related to overvoltage protection is smaller than in the past and the manufacturing cost is suppressed.

  In order to solve the above problems, a power supply device according to the present invention outputs a main power supply unit that outputs a main drive voltage to a load, and outputs a sub drive voltage to the load instead of the main power supply unit when the main drive voltage drops. A sub power supply unit, wherein the sub power source unit generates a sub drive voltage, an output terminal to which a load is connected, a sub drive voltage generator, and an output terminal. A voltage control type first switch provided between the first switch and a connection point between the first switch and the sub drive voltage generation unit, and the on / off state is switched according to the main drive voltage to thereby control the first switch. A second switch for changing the voltage of the main power supply unit, the output of the main power supply unit is connected to the connection point, the first switch serves as a drive current path by the main drive voltage and a drive current path by the sub drive voltage, When the main drive voltage is overvoltage, Switch on / off state is switched, the first switch is characterized in that it is configured to be turned off.

  In this configuration, the first switch provided in the sub power supply unit also serves as a drive current path by the main drive voltage output from the main power supply unit. When the main drive voltage is in an overvoltage state, the second switch is turned on / off, and the first switch is turned off. Therefore, according to this configuration, it is possible to prevent an overvoltage from being applied to the load even if the main power supply unit does not include a switch for overvoltage protection.

  As a specific configuration of the power supply device, for example, the second switch is connected to the connection point between the first switch and the sub drive voltage generation unit and the control terminal of the first switch, and the first switch is turned on when the second switch is turned on. A configuration in which the switch is turned off is conceivable.

  As a more specific configuration of the power supply device, for example, the sub power supply unit further includes a constant voltage diode, the first switch, the drain terminal is connected to the output terminal, and the source terminal is connected to the connection point. A P-channel field effect transistor, the second switch having an emitter connected to the connection point, a collector connected to the gate terminal which is the control terminal of the first switch, and a base connected to the cathode of the constant voltage diode. A configuration of a PNP type bipolar transistor is conceivable.

  According to this configuration, when the main drive voltage exceeds the set voltage of the constant voltage diode, the second switch is turned on and the first switch is turned off, so that an overvoltage is applied to the load. Can be prevented.

  The main power supply unit of the power supply device includes, for example, a circuit that generates a main drive voltage by converting a commercial AC voltage into a direct current, and the sub drive voltage generation unit boosts or reduces the DC output voltage of the primary battery or the secondary battery. Including, but not limited to, a circuit for generating a sub drive voltage by stepping down.

  According to the present invention, it is possible to provide a power supply apparatus in which the number of parts related to overvoltage protection is smaller than that in the past and the manufacturing cost is suppressed.

It is a circuit diagram of the power supply device which concerns on the Example of this invention. It is a circuit diagram of the main power supply part with which the power supply device shown in FIG. 1 was equipped. It is a circuit diagram of the switching control part with which the power supply device shown in FIG. 1 was equipped. It is an operation | movement waveform diagram of the power supply device shown in FIG. It is a circuit diagram of the conventional power supply device.

  Hereinafter, embodiments of a power supply device according to the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, a power supply device 1 according to an embodiment of the present invention outputs a main power supply unit 10 that outputs a main drive voltage from an output terminal T3, and outputs a sub drive voltage or the main drive voltage from an output terminal T2. And a sub power supply unit 20. The output terminal T3 of the main power supply unit 10 is connected to a connection terminal T1 provided in the sub power supply unit 20.

  As shown in FIG. 2, the main power supply unit 10 includes a DC voltage source 11, a switch SW3 and a coil L2 connected in series between the DC voltage source 11 and the output terminal T3, and a connection point between the switch SW3 and the coil L2. And a diode C3 having a cathode connected thereto and a capacitor C2 having one end connected to the output terminal T3. The anode of the diode D3 and the other end of the capacitor C2 are grounded.

  The DC voltage source 11 is configured by a circuit that converts a commercial AC voltage into a DC voltage and outputs a predetermined DC voltage, but is not limited thereto, and is configured by a primary battery, a secondary battery, or a large-capacity capacitor. May be.

  The main power supply unit 10 operates as a step-down DC / DC converter by turning on / off the switch SW3 by a switching control unit (not shown), and outputs a DC main drive voltage from the output terminal T3. In this embodiment, the main drive voltage is 5.2 [V].

  As shown in FIG. 1, the sub power supply unit 20 includes a DC voltage source 21, a coil L1, a diode D1, and a switch SW2, which are connected in series between the DC voltage source 21 and the output terminal T2, and a coil L1 and a diode D1. And a switch SW1 having one end (drain terminal) connected to the connection point. The other end (source terminal) of the switch SW1 is grounded.

  The coil L1, the diode D1, and the switch SW1 constitute the “sub drive voltage generation unit” of the present invention. The sub-drive voltage generator operates as a step-up DC / DC converter by turning on / off the switch SW1, which will be described later, and outputs a DC sub-drive voltage from the output terminal T2. In this embodiment, the sub drive voltage is 5.0 [V].

  The DC voltage source 21 is composed of a primary battery having a fully charged voltage lower than 5.0 [V], but is not limited thereto, and is composed of a secondary battery or a circuit capable of outputting a DC voltage. May be.

  The switch SW1 is formed of an N-channel field effect transistor having a drain terminal connected to a connection point between the coil L1 and the diode D1, and a source terminal grounded.

  The switch SW2 is composed of a P-channel field effect transistor having a drain terminal connected to the output terminal T2 and a source terminal connected to the cathode (that is, the connection terminal T1) of the diode D1 constituting the sub drive voltage generation unit. . The switch SW2 corresponds to the “first switch” of the present invention.

  The sub power supply unit 20 further includes a low voltage detection unit 22, a resistor R1 having one end connected to the output of the low voltage detection unit 22, and a resistor R3 having one end connected to the other end of the resistor R1. The other end of the resistor R3 is connected to a connection point (that is, a connection terminal T1) between the sub drive voltage generator and the switch SW2, and the other end of the resistor R1 is also connected to a gate terminal of the switch SW2.

  When the voltage of the DC voltage source 21 is normal, that is, when the voltage of the DC voltage source 21 is greater than a predetermined threshold, the low voltage detection unit 22 outputs a low level (0 [V]) voltage. At this time, the switch SW2 is turned on. On the other hand, the low voltage detector 22 does not output a specific voltage when the voltage of the DC voltage source 21 is smaller than a predetermined threshold. As a result, the voltage (control voltage) at the gate terminal of the switch SW2 becomes substantially equal to the voltage at the source terminal, and the switch SW2 is turned off. The voltage at the gate terminal and the source terminal of the switch SW2 is equal because the resistor R3 exists.

  The sub power supply unit 20 includes a resistor R4 having one end connected to the output terminal T2, a resistor R5 having one end connected to the other end of the resistor R4, a capacitor C1 having one end connected to the output terminal T2, and a switching control unit. 23. The other end of the resistor R5 and the other end of the capacitor C1 are grounded. The switching control unit 23 includes a terminal T4 connected to the connection point of the resistors R4 and R5 constituting the voltage dividing circuit, a terminal T5 connected to the output of the low voltage detection unit 22 via the resistor R1, and a switch. And a terminal T6 connected to the gate terminal of SW1.

  In this embodiment, the resistors R4 and R5 have the same resistance value. Therefore, a voltage that is ½ times the voltage output to the load 40 is input to the terminal T4 of the switching control unit 23. For example, when the main drive voltage (= 5.2 [V]) is output to the load 40, 2.6 [V] is input to the terminal T4 of the switching control unit 23.

  As shown in FIG. 3, the switching control unit 23 includes a reference voltage source 30, an error amplifier 31, a waveform generation unit 32, a PWM comparator 33, NOT circuits 34 and 36, and a NAND circuit 35. . The error amplifier 31 has a non-inverting input terminal (+) connected to the terminal T 4 and an inverting input terminal (−) connected to the reference voltage source 30. The PWM comparator 33 has an inverting input terminal (−) connected to the output terminal of the error amplifier 31 and a non-inverting input terminal (+) connected to the waveform generation unit 32. The NOT circuit 34 has an input terminal connected to the terminal T5. The NAND circuit 35 has a first input terminal connected to the output terminal of the PWM comparator 33 and a second input terminal connected to the output terminal of the NOT circuit 34. The NOT circuit 36 has an input terminal connected to the output terminal of the NAND circuit 35, and an output terminal connected to the terminal T6.

  The voltage of the reference voltage source 30 is 2.5 [V] which is slightly lower than 2.6 [V]. The waveform generator 32 generates a RAMP signal such as a triangular waveform or a sawtooth waveform.

  When the low voltage detection unit 22 detects that the voltage of the DC voltage source 21 is smaller than a predetermined threshold, that is, when the voltage at the terminal T5 is at a high level, the voltage at the terminal T6 is at a low level. Become. When the main drive voltage is output to the load 40, that is, when the voltage at the terminal T4 is larger than the voltage at the reference voltage source 30, the voltage at the terminal T6 is at the low level. In these cases, the switch SW1 is maintained in the off state, and the sub drive voltage generation unit does not perform the boosting operation.

  On the other hand, when the above two cases do not apply, the voltage at the terminal T6 changes each time the magnitude relationship between the error signal output from the error amplifier 31 and the RAMP signal output from the waveform generation unit 32 changes. As a result, the switch SW1 is repeatedly turned on / off, and the sub drive voltage generation unit outputs the sub drive voltage generated by the boosting operation.

  As shown in FIG. 1, the sub power supply unit 20 includes a PNP bipolar transistor Q having an emitter connected to the source terminal of the switch SW2 and a collector connected to the gate terminal of the switch SW2, and one end connected to the source terminal of the switch SW2. And a resistor R2 having the other end connected to the base of the bipolar transistor Q, and a constant voltage diode D2 having a cathode connected to the other end of the resistor R2. The anode of the constant voltage diode D2 is grounded.

  The bipolar transistor Q corresponds to the “second switch” of the present invention. In this embodiment, the set voltage of the constant voltage diode D2 is 5.6 [V].

  When the main drive voltage output from the main power supply unit 10 is normal, the constant voltage diode D2 is turned off. In this case, the bipolar transistor Q is maintained in the off state and does not affect the voltage at the gate terminal of the switch SW2.

  On the other hand, when the main drive voltage output from the main power supply unit 10 is in an overvoltage state exceeding 5.6 [V], the constant voltage diode D2 is turned on. Then, the voltage at the gate terminal of the switch SW2 becomes substantially equal to the voltage at the source terminal, and the switch SW2 is turned off. Thereby, the load 40 is protected from overvoltage.

  FIG. 4 is a waveform diagram showing the overvoltage protection operation of the power supply device 1 according to this embodiment. At time t1, when the voltage Vt1 (that is, the main drive voltage) of the connection terminal T1 changes from 5.2 [V] to 10 [V], the cathode voltage Vd2 of the constant voltage diode D2 changes from 5.2 [V]. It changes to 5.6 [V]. At the same time, the bipolar transistor Q is turned on, the switch SW2 is turned off, and the voltage Vt2 at the output terminal T2 drops from 5.2 [V] to 0 [V]. Thereafter, when the overvoltage state is eliminated at time t2, the voltage Vt2 returns to 5.2 [V].

  As described above, in the power supply device 1 according to the present embodiment, the main power supply unit 10 and the sub power supply are configured such that the switch SW2 of the sub power supply unit 20 serves as the drive current path using the main drive voltage and the drive current path using the sub drive voltage. Since the unit 20 is connected, it is possible to prevent the main drive voltage in the overvoltage state from being applied to the load 40 by changing the switch SW2 to the off state. In other words, according to the power supply device 1 according to the present embodiment, it is possible to prevent an overvoltage from being applied to the load 40 even if the main power supply unit 10 does not include a switch for overvoltage protection.

  Although the power supply device 1 according to the embodiment of the present invention has been described above, the configuration of the present invention is not limited to the configuration of the embodiment.

  For example, the main power supply unit 10 can have an arbitrary circuit configuration that can output a DC main drive voltage suitable for the load 40. Similarly, the sub drive voltage generation unit of the sub power supply unit 20 can also have an arbitrary circuit configuration (for example, a boost circuit and a step-down circuit) that can output a DC sub drive voltage suitable for the load 40.

  In the above embodiment, the bipolar transistor Q (second switch) is connected to the control terminal of the switch SW2 (first switch), and the first switch is turned off by switching the second switch from the off state to the on state. However, the first switch may be turned off by switching the second switch from the on state to the off state. That is, the second switch is turned on / off according to the main drive voltage. When the main drive voltage is overvoltage, the second switch is turned on / off, and the first switch is turned off. It only has to be.

DESCRIPTION OF SYMBOLS 1 Power supply device 10 Main power supply part 11 DC voltage source 20 Sub power supply part 21 DC voltage source 22 Low voltage detection part 23 Switching control part 30 Reference voltage source 31 Error amplifier 32 Waveform generation part 33 PWM comparator 34 NOT circuit 35 NAND circuit 36 NOT Circuit 40 Load C1, C2 Capacitor D1, D3 Diode D2 Constant voltage diode L1, L2 Coil Q Bipolar transistor ("second switch" of the present invention)
R1, R2, R3, R4, R5 Resistor SW1, SW3 Switch SW2 Switch ("first switch" of the present invention)

Claims (4)

A power supply apparatus comprising: a main power supply unit that outputs a main drive voltage to a load; and a sub power supply unit that outputs a sub drive voltage to the load instead of the main power supply unit when the main drive voltage drops. ,
The sub-power supply unit is
A sub-driving voltage generator for generating the sub-driving voltage;
An output terminal to which the load is connected;
A voltage control type first switch provided between the sub drive voltage generator and the output terminal;
A second switch that is connected to a connection point between the first switch and the sub-drive voltage generator, and that changes a voltage at a control terminal of the first switch by switching an on / off state according to the main drive voltage; With
The output of the main power supply unit is connected to the connection point, and the first switch serves as a drive current path by the main drive voltage and a drive current path by the sub drive voltage,
The power supply device is configured such that when the main drive voltage is in an overvoltage state, the second switch is turned on and off, and the first switch is turned off. The second switch is connected to the connection point and the control terminal;
The power supply device according to claim 1, wherein when the second switch is turned on, the first switch is turned off. The sub power supply unit further comprises a constant voltage diode,
The first switch is a P-channel field effect transistor having a drain terminal connected to the output terminal and a source terminal connected to the connection point,
The second switch has a PNP-type bipolar transistor having an emitter connected to the connection point, a collector connected to the gate terminal as the control terminal of the first switch, and a base connected to the cathode of the constant voltage diode. And
The power supply device according to claim 2, wherein when the main drive voltage exceeds a set voltage of the constant voltage diode, the second switch is turned on and the first switch is turned off. The main power supply unit includes a circuit that generates a main drive voltage by converting a commercial AC voltage into a direct current,
4. The circuit according to claim 1, wherein the sub drive voltage generation unit includes a circuit that generates the sub drive voltage by stepping up or down a DC output voltage of a primary battery or a secondary battery. The power supply device according to item.

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