JP5328483B2 - Emergency power supply - Google Patents

Description

  The present invention relates to an emergency power supply device, and more specifically, normally supplies alternating current from a commercial power source to a load, and converts the alternating current into direct current to charge a storage battery. When the commercial power supply fails, the direct current from the storage battery The present invention relates to an emergency power supply device that converts AC into AC and supplies it to a load.

  For example, a fire shutter is normally open, but when a fire breaks out, it detects fire and smoke and automatically closes to protect people from fire and smoke, and the outside leaks smoke. Isolate so that there is no. On the other hand, when a fire engine arrives, we want to start fire fighting activities by temporarily opening the fire shutter, but there are not a few cases where there is a power outage at this time. In such a case, an emergency power supply with a built-in storage battery Is required.

  This type of emergency power supply supplies power to the fire shutter (AC motor) by charging the storage battery with a commercial power supply during normal operation and generating AC power from the storage battery even if the commercial power supply fails in an emergency. it can. Such an emergency power supply is often installed as far as possible from the load from the operation side used in an emergency, and it is necessary to avoid the influence of noise generated in the power supply section to the external equipment as much as possible. is there.

  Since the conventional motor drive inverter device is exclusively for the purpose of improving the efficiency of operation, the current distortion caused by the rectification of the commercial power supply not only affects the commercial power supply side, but also the remote output by the rectangular wave AC output. Since the load (motor, etc.) is directly driven, the influence of noise on external devices is not limited. In recent years, the frequency of inverter control has been increased particularly, and the influence of noise on external devices tends to increase.

 Conventionally, this is an inverter device for full-wave rectification of a three-phase alternating current and smoothing with a smoothing capacitor, switching the obtained direct current voltage into a rectangular wave alternating current output, and supplying power to a load (motor). In addition to providing a noise filter for suppressing common mode noise between the full-wave rectifier circuit and the smoothing capacitor, connecting a snubber circuit in parallel with the rectifier diode of the full-wave rectifier circuit reduces conduction noise caused by switching control. An inverter device with reduced propagation is known (Patent Document 1).

JP 2000-166254 A

  However, when the load is directly driven by a rectangular wave AC output as in the conventional case, switching noise due to the rectangular wave AC output is propagated, which may adversely affect the device itself and other devices.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an emergency power supply apparatus that can generate a highly reliable operation with less noise due to a simple configuration. is there.

In order to solve the above problems, the emergency power supply apparatus according to the first aspect of the present invention normally supplies alternating current from a commercial power supply to the motor , converts the alternating current to direct current, and charges the storage battery. An emergency power supply device that converts a direct current from the storage battery into an alternating current and supplies the motor to the motor at the time of a power failure of the commercial power supply, and outputs the direct current from the storage battery to a rectangular wave alternating current by a semiconductor switching element having a three-phase full bridge configuration An inverter circuit unit for converting the inverter circuit unit into a PWM system, a filter unit for converting a rectangular wave AC output from the inverter circuit unit into a sine wave AC output, and an output of the filter unit An output voltage detecting means for detecting a voltage, and the detected voltage of the output voltage detecting means is compared with a predetermined threshold value, and the PWM control is performed in such a direction that the difference becomes zero. Output voltage stabilization means for performing feedback control via a unit, and further, low-pass filter means for inputting the output voltage detected by the output voltage detection means to the output voltage stabilization means of the next stage with a predetermined time constant delay Therefore, it is possible to suppress the generation of noise associated with the change in the output three-phase AC voltage due to the load fluctuation at the start or stop of the motor operation.

In the present invention, since the rectangular wave AC output from the inverter circuit unit is converted into a sine wave AC output and output, the influence of spike noise on external devices can be greatly reduced. In addition, since the output is sinusoidal, no noise or spark is generated, the product life can be extended, and a remote load (such as a fire shutter motor) can be driven with high reliability. In addition, because of the sine wave AC output, the load is not limited to a motor or the like and can be applied in a wide range.
In addition, since the AC output voltage stabilization means is provided, a constant AC voltage can be supplied to the load regardless of load fluctuations accompanying start / stop of the motor and fluctuations of the storage battery voltage accompanying charging / discharging of the storage battery. In other words, the period during which the output voltage can be kept constant by charging the storage battery once (apparent storage battery life) is greatly extended, and the reliability as an emergency power supply device is improved. In addition, it is possible to use a storage battery having a smaller capacity than before, and the introduction cost and running cost of the power supply device can be reduced.
Furthermore, even after an ac voltage exceeding a predetermined level cannot be supplied to the output due to the discharge of the storage battery, it is possible to output as much ac voltage as possible by not stopping the stabilization function of the output voltage stabilizing means. Become. Even if the AC output is smaller than the rated value, there is a possibility that the emergency situation can be avoided by supplying the load to the load. In addition, this is a preferable configuration as an emergency power supply device in the sense that there is a possibility that a disaster can be coped with in the unlikely event that the storage battery voltage has become insufficient. Further, since the output voltage stabilizing means is provided, there is no restriction on the load side, and it can be used other than the motor load, and the efficiency of the storage battery can be improved.
Further, by inserting the low-pass filter means having a predetermined time constant into the output voltage feedback loop, even if the output voltage changes suddenly due to a sudden load fluctuation or the like, the feedback voltage is relaxed by the filter means. As a result, the transient response of the output voltage stabilization means that attempts to restore the output voltage is also alleviated, and the generation of noise accompanying an abrupt transient response can be effectively suppressed.

In the second aspect of the present invention, the output voltage stabilizing means is configured to be able to perform a storage battery operation to near the discharge end voltage of the storage battery while maintaining an output amplitude substantially constant. To do.

According to a third aspect of the present invention, the circuit portion is hermetically sealed with a metal case, and the circuit between the filter means and the motor is separated by an insulating transformer.

  According to a fourth aspect of the present invention, there is provided inrush current mitigation means for mitigating inrush current from the storage battery at the time of replacement of the storage battery, and the inrush current mitigation means is provided between the power supply line from the storage battery and the ground line. A resistance voltage dividing circuit connected to the capacitor, a voltage dividing point of the resistance voltage dividing circuit and a ground wire, a capacitor for charging an inrush voltage associated with the storage battery connection with a predetermined time constant, and the ground wire And a semiconductor amplifying element connected in series and changing an internal resistance between the input and output terminals according to a charging voltage of the capacitor.

  In the present invention, since the inrush current when the storage battery block is connected (exchanged) to the emergency power supply device is reduced (soft-started), the occurrence of sparks at the connector portion can be prevented, and the storage battery can be replaced safely.

  In the fifth aspect of the present invention, the resistance connected in series to the power supply line of the storage battery and the terminal voltage of the resistance are detected and compared with a predetermined threshold, and the terminal voltage exceeds the predetermined threshold. An overcurrent detecting means for detecting an overcurrent; and a control section for quickly stopping the control rate of the PWM control section and restarting the control of the PWM control section by detecting the overcurrent by the overcurrent detection means; It is equipped with.

  According to the present invention, when an overcurrent exceeding a predetermined value is detected due to an overload or the like, the output of the PWM control unit is stopped to avoid a circuit and load failure and after the overcurrent is recovered. The operation is continued by restarting the output of the PWM controller. For this reason, even in the unlikely event, the output as an emergency power source can be achieved by continuing the output as much as possible without stopping the output completely.

  As described above, according to the present invention, by suppressing the occurrence of spike noise accompanying the inverter operation, the operation reliability of the device itself is improved and the noise given to the outside can be greatly reduced.

It is a principal part block diagram of the emergency power supply device by embodiment. It is a block diagram of the emergency power supply device by embodiment. It is a figure explaining the switching power supply by embodiment. It is a block diagram of the output voltage stabilization function part by embodiment. It is operation | movement explanatory drawing of the output voltage stabilization circuit by embodiment. It is the elements on larger scale of the inverter circuit part by embodiment. It is a figure which shows the inrush current relaxation circuit by embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a main part of an emergency power supply apparatus according to an embodiment. This emergency power supply 1 is rectangular by switching a direct current of a storage battery 2 for supplying power at the time of a power failure, a charger 4 for rectifying a commercial power source 3 at the time of a non-power failure, and charging the storage battery 2 at the time of a power failure. An inverter circuit unit 5 for converting to a wave AC output, a PWM control unit 6 for switching control of the inverter circuit unit 5 by a PWM (Pulse Width Modulation) method, and a rectangular wave AC output of the inverter circuit unit 5 as a sine wave AC output The LC filter 7 to be converted into the power, the insulation transformer 8 for insulating between the output of the LC filter 7 and the load 10 including the induction motor M and the like, and the commercial power supply 3 of the input is supplied to the load 10 when there is no power failure At the same time, an output switching means 9 for switching to the sine wave AC output of the insulating transformer 8 and supplying power to the load 10 is provided.

  With such a configuration, when the commercial power source 3 is input, the output switching means 9 is connected to the contact a side so that the input commercial power source is directly supplied to the load 10 and the storage battery 2 is charged by the charger 4. On the other hand, at the time of a power failure of the commercial power supply 3, a sine wave AC output is generated from the storage battery 2 via the inverter circuit unit 5 and the LC filter 7, and the output switching means 9 is connected to the contact b side to supply the sine wave AC output to the load 10. Power to

  In the present apparatus 1, the carrier frequency for PWM control is made relatively high (for example, 15 kHz), whereby the size and cost of the LC filter 7 and the like can be reduced, and the entire apparatus is made compact. Further, by making the carrier frequency equal to or higher than the audible frequency, the operation sound is reduced and the efficiency is improved.

  On the other hand, in the inverter circuit unit 5 that performs switching of a relatively large current (instantaneously about 100 A at the maximum), although the heat generation of the switching element is increased by increasing the carrier frequency, measures are taken by strengthening the heat sink. In addition, switching noise within the housing (that is, up to the primary side of the insulating transformer 8) is increased by increasing the carrier frequency, but various DC power supplies and inverter circuit units 5 for supplying power to the PWM control unit 6 and the like. Stable inverter operation is ensured by measures against noise described later. Further, since the rectangular wave AC output (PWM AC output) from the inverter circuit unit 5 is converted into a sine wave AC output by the LC filter 7, the influence of the harmonic noise based on the PWM control is changed from the inverter circuit unit 5 to the LC filter 7. This greatly reduces the influence of noise on external devices. Further, the circuit portion is hermetically sealed with a metal case, and the circuit between the LC filter 7 and the load 10 is separated (insulated) by the insulating transformer 8, thereby reducing the influence of noise applied to the outside. Details will be described below.

  FIG. 2 is a block diagram of the emergency power supply device according to the embodiment, and shows an application example to a three-phase AC power supply device. In the figure, the three-phase alternating current from the commercial power source 3 is input to the b-side terminal of the output switching means 9 via the input terminal 11 and also to the control board 13 side via the connector 12. In this control board 13, the rectifier circuit 14 full-wave rectifies the single-phase input (line voltage AC200V) of the commercial power supply and smoothes the rectified output by a capacitor to generate DC280V. Further, the charger 4 charges the storage battery (block) 2 having a nominal 192V by using this DC280V. Further, the switching (SW) power supply 15 performs DC-DC conversion on the DC 280V input by a switching method to generate a plurality of types of control DC voltages (DC 24V, DC 15V, DC 5V) each having a stabilized output voltage.

<Measures against noise in switching power supplies>
FIG. 3 is a diagram illustrating the switching power supply 15 according to the embodiment. Although various known power sources can be used as the switching power source 15, the simplest single-end flyback switching power source 15 is used here to explain the noise countermeasures taken in the present embodiment. A case will be described as an example.

  In FIG. 3, energy is stored in the transformer T while the FET element Q8 is ON, and energy is supplied to the load 42 by discharging the capacitor C3. Next, during the period when the FET element Q8 is OFF, the energy of the transformer T is supplied to the capacitor C3 and the load 42 through the diode D4. Hereinafter, these are repeated. In this state, the output DC voltage Vo is divided by the Zener diode ZD and the bias resistor Rb, and the terminal voltage of the resistor Rb is applied to the light emitting diode of the photocoupler 44. As a result, light proportional to the output voltage Vo is emitted from the light emitting diode, and a control signal proportional to the received light intensity is output to the emitter in the phototransistor receiving the light, and this control signal is controlled by the SW control IC 43. Input to terminal C. The SW control IC 43 performs feedback control based on the control signal of the control terminal C so that the output voltage Vo of the switching power supply 15 becomes constant.

  In the present embodiment, the ferrite bead FB is fitted to the control terminal C of the SW control IC 43, so that mixing of switching noise to the control signal fed back from the output is suppressed, and a stable output voltage Vo is obtained. As the SW control IC 43, for example, a power integration equivalent to MIP0224SY can be used. The noise countermeasures described above are the same for the DC 24V, DC 15V, and DC 5V switching power supplies.

  Of the control voltage generated by the switching power supply 15, DC 15 V is supplied to a driver circuit (DR) 16 that drives the inverter circuit unit 5, and DC 5 V is supplied to a logic circuit such as the CPU 18 or the PWM control unit 6. . Furthermore, DC24V is used as a DC power source for generating DC15V and DC5V, and also used as a driving power source for relays and the like.

  Returning to FIG. 2, a capacitor C <b> 1 and a Zener for absorbing spike noise and the like generated by switching of a large current in the inverter circuit unit 5 are provided between the power supply line of each control power source (DC15V, DC5V) and the ground line. A diode Z1 is provided. For example, a 18V Zener diode is connected to the DC15V power line, and a 6.2V Zener diode is connected to the DC5V power line. In this embodiment, a plurality of small sizes are dispersedly arranged as shown in the figure.

  Preferably, a plurality of capacitors (ceramic capacitors) and a plurality of Zener diodes are alternately distributed along the power supply line, so that spike noise generated in the circuit is absorbed in the vicinity of the generation point, and the power supply line is It is not allowed to propagate. FIG. 2 shows a connection image of the capacitor C1 and the Zener diode Z1 in the DC15V power line. Although not shown, the same applies to the DC5V power supply line.

  In the present embodiment, DC 15V is supplied to the PWM control driver circuit 16 and, for example, FET elements Q1 to Q6 as semiconductor switching elements constituting the inverter circuit unit 5 are supplied with DC 200V (nominal 192V) from the storage battery 2. Power is being supplied. Since these FET elements Q1 to Q6 switch a current of 100 A at approximately 200 V at 15 kHz, if the ground-to-ground connection between the two DC power sources is not sufficient, these ground levels will fluctuate according to the load current, It can also cause unstable operation.

  For this reason, the connection between the ground lines is strengthened by connecting the ground line of DC15V and the ground line of the storage battery 2 at a plurality of locations by a plurality of pattern wirings, and the ground level between the two DC power sources is stabilized. ing. In FIG. 2, the state which strengthened the connection between each earth line of DC15V and the storage battery 2 is shown by the thick continuous line. In addition, although not shown in figure, also about DC24V power supply and DC5V power supply, the connection of each earth line and the earth line of the storage battery 2 is strengthened similarly to the above. Thereby, stable operation of each circuit unit is obtained.

<Starting the inverter circuit>
The power failure detection unit 17 performs full-wave rectification on the input commercial power supply to detect the PP voltage, and detects the power failure state when the PP voltage falls below a predetermined value (for example, 80% or less). CPU 18 is notified of this. The CPU 18 activates the PWM control unit 6 in response to the notification of the power failure and starts inverter control.

  The inverter circuit unit 5 includes FET elements Q1 to Q6 having a three-phase full bridge configuration, and a DC voltage (nominal 192 V) from the storage battery 2 according to the PWM control signals U to W sent from the PWM control unit 6 through the driver circuit 16. Are switched to a three-phase PWM wave AC voltage. As an example of the semiconductor switching elements Q1 to Q6, n-channel power MOSFET elements excellent in high-speed switching are used, and unillustrated parasitic diodes (commutation) connected in antiparallel to the FET elements Q1 to Q6, respectively. Diode). When switching a large current, a plurality of MOSFET elements may be used in parallel, or an insulated gate bipolar transistor (IGBT) element may be used instead of the MOSFET element.

  Further, the three-phase rectangular wave AC output (three-phase PWM output) output from the inverter circuit unit 5 is converted into a three-phase sine wave AC by the LC filter 7. Further, this three-phase sine wave AC output is input to the primary winding of the isolation transformer 8, and the three-phase AC output separated from the secondary winding (ie, insulated from the inverter circuit unit 5) is output. The signal is output to the output terminal 23 via the switching means 9. In addition, although the output switching means 9 of this example is set as the structure switched automatically in connection with the power failure detection of the power failure detection part 17, you may comprise by another means, such as manual switching.

<Stabilization of three-phase sine wave AC output>
In this embodiment, the output voltage stabilization function of the three-phase AC voltage is provided, so that the output three-way power can be obtained regardless of the load fluctuation accompanying the start / stop of the motor operation and the fluctuation of the storage battery voltage due to charging / discharging of the storage battery 2. The phase AC voltage is configured to be constant. In FIG. 2, the output voltage stabilization function includes an output voltage detection unit 24 that detects the output voltage of the power supply device, and a PWM control unit 6 that delays the detected output voltage with a predetermined time constant (for example, approximately 1 second). Are realized by a low-pass filter (LPF) 25 that feeds back to the output and an output voltage stabilization circuit 6a in the PWM controller 6 that controls the output voltage to be constant according to the feedback input. This will be specifically described below.

  FIG. 4 shows a block diagram of the output voltage stabilization function unit. In the figure, the output voltage detection unit 24 performs full-wave rectification on the secondary side voltages u to w of the isolation transformer 8 using a diode bridge, and smoothes the rectified output using a smoothing capacitor C6. P) A detection signal D corresponding to the voltage is output to a low-pass filter (LPF) 25.

  In the LPF 25, the input detection signal D is divided by the Zener diode ZD2 and the bias resistor R6, and the terminal voltage of the resistor R6 is applied to the light emitting diode of the photocoupler 26. As a result, the light emitting diode emits light proportional to the detection signal D, and a phototransistor (emitter follower) receiving the light outputs a detection D proportional to the received light intensity to the emitter. The detection signal D is extracted via the variable resistor VR and further input to a low-pass filter circuit (integration circuit) including a resistor R7, a capacitor C7, and an operational amplifier (OAP) 27.

  The operational amplifier (OAP) 27 compares the detection signal D with a predetermined threshold Vr (corresponding to the rated output voltage of the emergency power supply device), amplifies the difference signal with a predetermined time constant delay, and obtains the gain obtained. The control signal G is input to the output voltage stabilization circuit 6 a in the PWM control unit 6. The gain control signal G as an example shows a higher level as the detection signal D is lower than the predetermined threshold Vr, and the level decreases as the detection signal D approaches the predetermined threshold Vr. Further, when it is higher than the predetermined threshold value Vr, a low level is output.

  In the output voltage stabilizing circuit 6a, the sine wave oscillator (OSC) 32 generates a sine wave AC signal S having an amplitude proportional to the level of the gain control signal G, and the triangular wave OSC 33 generates a triangular wave AC signal T having a constant amplitude. ing. The PWM modulation unit 34 compares the sine wave AC signal S from the sine wave OSC 32 with the triangle wave AC signal T from the triangle wave OSC 33 to generate PWM modulated PWM control signals U to W.

  FIG. 5 is an operation explanatory diagram of the output voltage stabilization circuit 6a. FIG. 5A shows a case where the storage battery voltage is relatively high (for example, 230 V) due to charging of the storage battery 2. In this case, even if the pulse width of the PWM control signal U is relatively narrow, for example, U1 in the figure, the sine wave AC signal u1 having the required amplitude is obtained at the three-phase AC output, so the level of the gain control signal G is The amplitude of the sine wave AC signal S1 generated in response to this is relatively low. Accordingly, the pulse width of the PWM control signal U1 is also relatively narrow, and a three-phase alternating current u1 having a required amplitude is obtained with a small PWM control rate (duty ratio) at the output of the inverter circuit unit 5.

  FIG. 5B shows a case where the storage battery voltage is relatively low (for example, 190 V) due to the discharge of the storage battery 2. In this case, since the output amplitude of the three-phase alternating current decreases, the level of the gain control signal G becomes relatively high, and the amplitude of the sinusoidal alternating current signal S2 generated accordingly increases. Accordingly, the pulse width of the PWM control signal U2 is also relatively wide, and the three-phase alternating current u2 having a required amplitude can be obtained from the output of the inverter circuit unit 5 with a wide PWM control rate. The same applies to the other v and w phases.

  Conventionally, the three-phase AC output voltage fluctuates by about ± 30% according to the voltage fluctuation of the storage battery 2, but in this embodiment, the output amplitude is maintained substantially constant by providing the output voltage stabilization circuit 6a. However, it is possible to perform the storage battery operation up to the vicinity of the discharge end voltage of the storage battery 2. Thereby, the lifetime of the storage battery which can be continuously operated by one charge was extended to about 1.5 to 2 times the conventional one. Preferably, the emergency power supply device does not stop the output stabilization control described in FIG. 4 until the voltage of the storage battery 2 becomes approximately 0V. For this reason, this emergency power supply device will continue to output the AC voltage as much as possible even after it becomes unable to output the rated AC voltage to the output, and tries to fulfill the role as an emergency power supply as much as possible. It is configured to do.

  Further, in this embodiment, the LPF 25 having a predetermined time constant is provided in the output voltage feedback loop, so that the output three-phase AC voltages u to w are suddenly changed due to a sudden load fluctuation accompanying the start / stop of the motor operation. Even so, the sudden change in the feedback signal D is moderated by the LPF 25 as required. As a result, the transient response operation of the output voltage stabilization circuit 6a which attempts to restore the AC output voltage is also alleviated, and the generation of noise accompanying a rapid transient response can be effectively suppressed.

<Noise countermeasures in the inverter circuit>
Next, some noise countermeasures in the inverter circuit unit 5 will be described. FIG. 6 is an enlarged view of a portion related to the inverter control of FIG. One of the noise countermeasures is to wire between the output of each driver circuit 16 and the gate input of each FET element Q1 to Q6 by a shield line, and to cover the shielded shield line (shown by a dotted line in the figure) on the FET element side. It is grounded at one point. Since the FET elements Q1 to Q6 switch a current of about 100 A at a high speed (for example, 15 kHz), spike noise due to harmonic components may wrap around the gate circuit due to electrostatic coupling or the like, and the FET element may be unstablely operated. . In the present embodiment, the gate circuits of the FET elements Q1 to Q6 are shut off from the outside (electrostatic shield), whereby noise is bypassed to the ground side, and a stable switching operation of the FET elements Q1 to Q6 is ensured.

  In the present embodiment, the amorphous beads AB are fitted to the drain terminals of the FET elements Q1 to Q6, thereby suppressing the occurrence of spike noise associated with the switching of the FET elements. An example of the amorphous beads AB uses a cobalt-based amorphous alloy having a small coercive force at a high frequency as the core material.

  Generally, when a semiconductor element such as a diode transits from ON to OFF, a current in the reverse direction (reverse recovery current) temporarily flows through the PN junction. The magnetization state of the amorphous beads AB is in a saturated state during the period in which the forward current flows, and shows almost no inductance, but a reverse current (reverse recovery current) will flow after the forward current is cut off. In this period, the inductance rapidly increases, and this large inductance functions to block the reverse recovery current, so that a sudden change in the recovery current is alleviated (so-called soft recovery). As a result, the rapid change in the reverse recovery current is alleviated, and the generation of a noise voltage proportional to the differentiation of the current change is sufficiently suppressed.

  In the case of the amorphous beads AB, there is an advantage that the slope of the current at the time of turn-off is not changed because the inductance hardly shows until the current zero crosses even during the period in which the forward current decreases toward zero. Further, in the example of FIG. 6, amorphous beads AB are fitted to the drain terminals of the FET elements Q to Q6, but the present invention is not limited to this. Amorphous beads AB may be fitted to the source terminals of the FET elements Q1 to Q6.

<Destruction prevention circuit of FET element>
Further, in the present embodiment, a current limiting inductor L1 between each FET element Q1, Q3, Q5 constituting the upper arm of the inverter circuit section 5 and the DC power supply, and a diode for preventing back electromotive force of the inductor A parallel circuit consisting of D2 is inserted. This will be described below.

  Generally, a power MOSFET element has a parasitic diode (commonly referred to as an internal diode) reversely connected to the inside due to its structure, but in the present embodiment, the internal diode D1 is actively used as a commutation diode. doing. Furthermore, in this type of inverter circuit unit 5, the FET elements Q1, Q3, Q5 constituting the upper arm and the lower arm FET elements Q2, Q4, Q6 directly connected to these are not simultaneously turned on, but the load When the LC filter 7, the motor 10, etc. are connected to each other, for example, even when the upper arm FET element Q1 is OFF, the internal diode D1 of the FET element Q1 becomes conductive due to the back electromotive force generated by the inductance of the load. There is a period.

  On the other hand, each FET element constituting the lower arm is turned ON and OFF during this period. For example, during the period when the FET element Q2 is ON, the internal diode D1 of the FET element Q1 is reverse-biased from the conductive state. However, since the reverse recovery current flows through the internal diode D1, there is a moment (approximately 100 nsec) when both the internal diode D1 and the FET element Q2 are in a conductive state. At this time, a large current flows, and in the worst case, the device is destroyed. Therefore, in the present embodiment, a small inductor L1 for current limiting (for example, about 1 μH) and a counter electromotive force generated by the inductor L1 are limited so that the reverse recovery current flowing during the reverse recovery time of the internal diode D1 is limited. Diode D2 (forward current of about 10 A, forward response speed of 50 nS or less).

<Other measures>
Returning to FIG. 2, in the present embodiment, an inrush current mitigation circuit 21 is provided in the power supply line of the storage battery 2 to mitigate the inrush current rush that occurs when the storage battery block 2 is turned on (connected). FIG. 7 shows the configuration of the inrush current mitigation circuit according to the embodiment. In FIG. 7, the connector CNa of an example can accommodate a total of 40 1.2V storage batteries 2 and can be connected in series to supply a nominal 48V direct current per connector. Further, the power supply device 1 can supply a nominal DC voltage of 192 V as a whole by connecting the four connectors CNa to CNd in series.

  When such a storage battery block (192 V) is initially connected to the power supply device 1, since a large inrush current may flow through the inverter circuit unit 5, a spark may be generated at the connector terminal. An inrush current mitigating circuit 21 for mitigating the inrush current is provided. The inrush current reducing circuit 21 includes a resistance voltage dividing circuit composed of resistors R2 and R3, a capacitor C2 charged with a predetermined time constant by a divided voltage of the resistance voltage dividing circuit, and a charging voltage of the capacitor C2 The FET element Q7 that makes the internal resistance between the source and drain variable by being added to the gate terminal, the Zener diode Z2 that clamps the charging voltage of the capacitor C2, and the charge stored in the capacitor C2 when the storage battery block is removed. And a diode D3 for resetting the voltage. Although not shown, when the current capacity of the FET element Q7 is insufficient, a plurality of FET elements having the same characteristics can be used in parallel.

  With such a configuration, when the storage battery voltage Vi (192 V) is input to the inverter circuit unit 5 at this time, this voltage Vi is divided by the resistors R2 and R3. It is charged with a constant. This charging voltage is applied to the gate of the FET element Q7 through the resistor R4, thereby gradually increasing the drain current of the FET element Q7. Then, until about 1 second elapses, the FET element Q7 is completely turned on, thus completing the soft start when the storage battery block is inserted.

  Further, in the present embodiment, an overcurrent detection unit 22 is provided on the power supply line of the storage battery 2 to prevent an overcurrent exceeding a predetermined amount from flowing into the inverter circuit unit 5. Specifically, an overcurrent detection resistor (for example, 8.3 mΩ) Rs is inserted in series with the power supply line of the storage battery 2, and a shield is provided between both ends of the resistor Rs and the input of the overcurrent detection unit 22. Each of the shielded shielded wires is grounded at one point on the overcurrent detection unit side.

  In addition, although the case where the whole storage battery block was initially supplied was described in the said embodiment, it is not restricted to this. Since all the storage batteries 2 are connected in series, even when any one of the connectors CN or the storage battery 2 is removed, the input voltage Vi drops to 0V. After that, when the removed connector CN or the storage battery 2 is reconnected, Vi = 192V is reintroduced into the inverter circuit unit 5, and the soft start is resumed as described above. Therefore, according to this embodiment, even when one storage battery is replaced, a spark does not fly to the connector contact, and the storage battery 2 can be replaced safely.

  Note that the storage battery monitoring unit 19 in FIG. 2 monitors the input voltage Vi of the storage battery power supply line, and if it is detected that the voltage Vi is below a predetermined threshold (for example, 190 V), notifies the CPU 18 of that fact. Receiving this, the CPU 18 displays on the display unit 20 described later that the storage battery voltage has fallen below a predetermined threshold, and thereafter continues the PWM control with the output stabilization control described in FIG.

  Moreover, in this Embodiment, the overcurrent detection part 22 is provided in the electric power feeding line of a storage battery. The overcurrent detection unit 22 detects and amplifies the terminal voltage of the resistor Rs connected in series with the storage battery power supply line, and at the same time, a first predetermined threshold value that does not cause any other trouble to the amplified output and the power supply circuit. (For example, when the amplified output exceeds the first predetermined threshold value by comparing with an average current of about 110 A, which is increased by 10%), the PWM control unit 6 immediately stops the PWM output. In addition to protecting the circuit and the load from failure, the output is restarted when the value falls below a predetermined threshold.

  Further, in the present embodiment, a display unit 20 for displaying various information generated by the operation of the emergency power supply device is provided, and the display unit 20 and the CPU 18 are connected by a bus line 20a. Yes. The CPU 18 transfers data of characters and numbers to the display unit 20 through the bus line 20a. However, since the garbled characters may occur due to switching noise from the inverter circuit unit 5 or the like, each of the bus lines 20a For example, a low-pass filter including a series resistor and a parallel capacitor is inserted into the signal line to reduce the influence of noise.

  In the above-described embodiment, the case where the MOSFET element is used as the semiconductor switching element has been described. However, the present invention is not limited to this. For example, it is obvious that an IGBT element may be used.

DESCRIPTION OF SYMBOLS 1 Emergency power supply device 2 Storage battery 3 Commercial power supply 4 Charger 5 Inverter circuit part 6 PWM control part 7 LC filter 8 Insulation transformer 9 Output switching means 10 Load 11 Input terminal 12 Connector 14 Rectification circuit 15 Switching (SW) power supply 16 Driver circuit 17 Power failure detection unit 18 CPU
19 Storage Battery Monitoring Unit 20 Display Unit 21 Inrush Current Mitigation Circuit 22 Overcurrent Detection Unit 23 Output Terminal 24 Output Voltage Detection Unit 25 Low-Pass Filter Unit

Claims (5)

Normally, AC from a commercial power supply is supplied to the motor , and the AC is converted to DC to charge the storage battery. When the commercial power supply fails, the DC from the storage battery is converted to AC and supplied to the motor. Power supply unit for
An inverter circuit unit for converting a direct current from the storage battery into a rectangular wave alternating current output by a semiconductor switching element having a three-phase full bridge configuration;
A PWM control unit for controlling the inverter circuit unit by a PWM method;
Filter means for converting the rectangular wave AC output from the inverter circuit unit into a sine wave AC output ;
Output voltage detection means for detecting the output voltage of the filter means;
An output voltage stabilizing unit that performs feedback control via the PWM control unit in a direction in which the detected voltage of the output voltage detecting unit is compared with a predetermined threshold and the difference becomes zero;
Furthermore, by having a low-pass filter means for inputting the output voltage detected by the output voltage detection means to the output voltage stabilization means of the next stage with a predetermined time constant delay, it is possible to cause a load fluctuation when starting or stopping the motor operation. An emergency power supply device that suppresses the generation of noise associated with a change in output three-phase AC voltage. 2. The emergency power supply according to claim 1, wherein the output voltage stabilizing means is configured to be able to operate the storage battery to near the discharge end voltage of the storage battery while maintaining the output amplitude substantially constant. apparatus. 3. The emergency power supply apparatus according to claim 1, wherein the circuit portion is sealed with a metal case, and the circuit between the filter means and the motor is separated by an insulating transformer. Inrush current relaxation means for relaxing the inrush current from the storage battery when the storage battery is replaced,
The inrush current mitigating means includes a resistance voltage dividing circuit connected between a power supply line from a storage battery and a ground line;
A capacitor connected between a voltage dividing point of the resistance voltage dividing circuit and a ground wire, and charging a rush voltage associated with the storage battery connection with a predetermined time constant;
Connected to said ground wire in series, according to any one of claims 1 to 3, the semiconductor amplifying element for changing an internal resistance between the input and output terminals in accordance with the charging voltage, comprising the said capacitor Emergency power supply. A resistor connected in series to the feeder of the storage battery;
Overcurrent detecting means for detecting a terminal voltage of the resistor and comparing it with a predetermined threshold, and detecting an overcurrent when the terminal voltage exceeds the predetermined threshold;
A control unit that stops the control of the PWM control unit by detecting the overcurrent by the overcurrent detection unit and restarts the control of the PWM control unit after the overcurrent is recovered. The emergency power supply device according to any one of claims 1 to 4 .

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