JP2008128897A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device capable of more rapidly detecting instant service interruption of AC power supply even when a capacitor is inserted between AC power supply lines on the input side of a direct current power supply circuit. <P>SOLUTION: An instant service interruption detecting circuit 5 monitors the gradients of the voltage waveforms of two phases (R phase and S phase) of a three-phase commercial AC power supply 2 and the potential difference between the two phases (R phase and S phase), and, when the all the gradients are under a threshold or the state that the potential difference is under a threshold continues for predetermined time or longer, detects the instant service interruption of the commercial AC power supply 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply device that includes a DC power supply circuit that rectifies AC power supplied from a three-phase AC power supply via an AC power supply line into a DC, and a capacitor that is inserted between the AC power supply lines.

In electrical and electronic equipment that is supplied with power from a commercial AC power supply, if the occurrence of a momentary power failure is detected, assuming that the power supply momentarily stops, that is, a momentary power failure occurs, a predetermined process is performed. There is something to do. For example, in a device using a microcomputer, processing such as saving data is performed in order to prevent destruction of control data. In Patent Document 1, the alternating current power supply voltage is converted into a waveform only on the positive direction side and monitored. When this voltage falls below the threshold voltage, the LED indicating the operation status is turned off to reduce power consumption, and the microcomputer An uninterruptible device is disclosed that maintains the power to hold the stored contents of. According to this, when the input AC power supply voltage falls below the reference voltage value, the occurrence of an instantaneous power failure is detected.
Japanese Patent Laid-Open No. 10-080073

  However, a capacitor is often inserted between the AC power supply lines on the input side for the purpose of removing noise superimposed on the power supply lines. For this reason, even if an instantaneous power failure occurs, the AC voltage level does not immediately decrease due to the electric charge accumulated in the capacitor, and it takes a relatively long time to fall below the threshold voltage. Therefore, there is a problem that detection of instantaneous power failure is delayed.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply that can detect an instantaneous power failure of an AC power supply more quickly even when a capacitor is inserted between AC power supply lines on the input side of the DC power supply circuit. To provide an apparatus.

  According to the power supply device of claim 1, the slope of any two-phase voltage waveform of the three-phase AC power supply is monitored, and the state in which both of the voltage waveform slopes are less than the threshold value is a predetermined time or more. If it continues, it detects that an instantaneous power failure occurred in the AC power supply. When an instantaneous power failure occurs, the voltage of each phase gradually decreases due to the influence of a capacitor inserted between the phases, but the slope of the voltage waveform at this time becomes smaller than in normal times. Since the instantaneous power failure detection means detects the instantaneous power failure based on such a change in the slope of the voltage waveform, the instantaneous power failure can be detected quickly even when a capacitor is inserted between the phases.

  According to the power supply device of claim 2, the voltage difference between the two phases is also monitored, and an instantaneous power failure occurs even when the condition that the voltage difference is less than the threshold value continues for a predetermined time or more is satisfied. Detect that If an instantaneous power failure occurs, the voltage difference between the phases is almost eliminated, so that the instantaneous power failure detection means can also detect the instantaneous power failure more reliably by monitoring this voltage difference.

  According to the power supply device of the third aspect, the predetermined time in the first and second aspects is set to two or more of the AC power supply period, so that erroneous detection based on temporary power supply fluctuation due to the influence of noise or the like is performed. Eliminating it, it is possible to reliably detect an instantaneous power failure.

  According to a fourth aspect of the present invention, the voltage level of the two phases is detected every predetermined period, and the amount of change between the current detection value and the past detection value between the phases is calculated. The counting means counts when the amount of change is less than the threshold value, and resets the count value if either one is greater than or equal to the threshold value, and the count value reaches a preset detection value. Then, an instantaneous power failure is detected. Therefore, the period during which the change in the slope of the voltage waveform is small can be integrated by the counting means, and an instantaneous power failure can be detected based on the integrated value.

  According to the power supply device of the fifth aspect, the counting means calculates a difference between the voltage detection values between the two phases at the same detection timing, and counts even when a condition that the difference is less than the threshold value is satisfied. If the difference between the detected values is equal to or greater than the threshold value, the count value is reset. Therefore, even when the difference between the detected voltage values is reduced, the integration is performed by the counting means in the same manner as in the fourth aspect. A power failure can be detected more reliably.

Hereinafter, an embodiment in which the present invention is applied to a power supply apparatus that supplies power to an actuator of a robot will be described with reference to the drawings.
FIG. 1 shows an electrical configuration of the power supply apparatus. The power supply device 1 includes a DC power supply circuit 4 for rectifying and smoothing power supplied from, for example, a three-phase 200 V commercial AC power supply (corresponding to a three-phase AC power supply) 2 and supplying the rectified and smoothed power to the industrial robot 3 as a load. In addition, an instantaneous power failure detection circuit (corresponding to an instantaneous power failure detection means) 5 for detecting an instantaneous power failure in the commercial AC power source 2 is configured.

  The DC power supply circuit 4 includes a full-wave rectifier circuit 6 and a smoothing capacitor 7, and R, S, and T phase outputs of the commercial AC power supply 2 are connected to a switch 8 and an AC power supply line 9 r. It is connected to the input side of the full-wave rectifier circuit 6 through 9s and 9t. Noise removing capacitors 10, 11, and 12 are connected between the AC power supply lines 9r to 9t, respectively. The DC power output from the full-wave rectifier circuit 6 is supplied to the robot 3 via DC power lines 13a and 13b, and a smoothing capacitor 7 is connected between the DC power lines 13a and 13b. The full-wave rectifier circuit 6 has a known configuration in which six rectifier elements are connected in a three-phase bridge shape.

  On the other hand, the instantaneous power failure detection circuit 5 includes a control unit (corresponding to a change amount calculation unit and a count unit) 14 that detects an instantaneous power failure of the commercial AC power supply 2 and a level at which the input voltage level can be input to the control unit 14. And a level conversion circuit 15 that outputs the converted signal. The level conversion circuit 15 is supplied with R-phase and S-phase AC voltages from the AC power supply lines 9r and 9s, and the level conversion circuit 15 controls the input AC voltage as voltage signals Vr and Vs obtained by level conversion. It outputs to the part 14.

  The control unit 14 is mainly configured by a microcomputer having a CPU 14a, an A / D converter 14b, a memory 14c, and the like. Although details will be described later, the control unit 14 is commercialized based on voltage signals Vr and Vs from the level conversion circuit 15. An instantaneous power failure of the AC power supply 2 is detected. When an instantaneous power failure is detected, an instantaneous power failure detection signal Sa is output to an engine board (not shown) that drives and controls the actuator of the robot 3.

  The voltage signals Vr and Vs input to the control unit 14 are converted into digital values by the A / D converter 14b, and the CPU 14a samples the converted data in a predetermined cycle, every 1 ms in this embodiment, and stores it in the memory 14c. Configured to write. In addition, the reference (ground) potential in the control unit 14 is the same potential as that of the DC power supply line 13b. Therefore, the waveforms of the voltage signals Vr and Vs are pulsating current waveforms that are half-wave rectified as shown in FIG. Become.

  In FIG. 2, the latest conversion data of the voltage signal Vr is indicated as newVr, the conversion data before 1 ms is indicated as old1Vr, the data before 2 ms is indicated as old2Vr, and the data before 3 ms is indicated as old3Vr. Similarly, the voltage signal Vs is expressed as newVs, old1Vs, old2Vs, old3Vs.

Next, the operation of the above configuration will be described with reference to FIG.
FIG. 3 is a flowchart showing the control contents of the CPU 14a during the instantaneous power failure detection process. The CPU 14a performs initial setting in step S1, and resets the Δ flag (delta_flg), the comparison flag (comp_flg), and the count value (cnt). In step S2, the process waits for 1 ms, which is the sampling interval, and proceeds to step S3 and subsequent steps after 1 ms.

In step S3, difference data ΔVr between the latest sampling data newVr of voltage signal Vr at that time and data old3Vr 3 ms before is calculated based on the following equation. Similarly, ΔVs is calculated for the voltage signal Vs.
ΔVr = newVr-old3Vr
ΔVs = newVs-old3Vs
ΔVr and ΔVs correspond to the gradient of the AC voltage waveform and the amount of change in the AC voltage.

  Subsequently, the calculated values of ΔVr and ΔVs are confirmed, and when both are equal to or lower than the threshold value Vth (details will be described later, for example, 400 mV) (“YES” in both steps S4 and S5), the voltage Since both of the rising degrees of the signals Vr and Vs indicate a small state, the process proceeds to step S6, and the Δ flag is set (delta_flg = 1). If either one of ΔVr and ΔVs is larger than the threshold value Vth (“NO” in any of steps S4 and S5), it indicates a state in which the degree of increase in the AC power supply voltage is normal. In step S7, the Δ flag is reset (delta_flg = 0).

  In step S8, a difference A between the voltage data newVr and newVs at that time is calculated. In step S9, the value of the calculated difference data A is confirmed, and when the value is equal to or lower than a threshold value Vth (for example, 400 mV) (“YES”), it is determined that the two-phase potential difference of the commercial AC power supply 2 is small. In step S10, the comparison flag is set (comp_flg = 1). If the value of the difference data A is greater than the threshold value Vth (“NO”), it is determined that the two-phase potential difference of the commercial AC power supply 2 is normal, the process proceeds to step S11, and the comparison flag is reset ( comp_flg = 0).

  The threshold value Vth is smaller than the amount of change while the voltage signals Vr and Vs are rising when the supply state of AC power is normal, and the engine board performs PWM control of the actuator of the robot 3. In this case, it is necessary to set a value larger than the noise superimposed on the voltage signals Vr and Vs. Therefore, as a result of measuring these values in the normal state, the amount of change when the voltage signal rises (in this embodiment, for 3 ms) is 207 V / 47 Hz in the state of the commercial AC power supply 2 (the voltage change amount is the smallest). Condition), the noise superimposed on the voltage signal was about 325 mV when the state of the commercial AC power supply 2 was 253 V / 63 Hz (a condition that maximizes the PWM noise). Therefore, in this embodiment, the threshold value Vth is set to 400 mV which is a value between them.

  In step S12, the state of the Δ flag is confirmed. If the Δ flag is set (“YES”), the process proceeds to step S13, and the count value is incremented (cnt = cnt + 1). If the Δ flag has been reset (“NO”), the process proceeds to step S14 to check the state of the comparison flag. If the comparison flag is set (“YES”), the process proceeds to step S13. If the comparison flag is reset ("NO"), the process proceeds to step S15, and the count value is reset (cnt = 0).

In step S16, the count value is confirmed. If the count value is equal to or greater than the instantaneous power failure detection value “45” (cnt ≧ 45) (“YES”), the state where the change in the AC power supply voltage is abnormal continues for 45 ms. Therefore, the instantaneous power failure detection signal Sa is output to the engine board (step S17), and the process is terminated. Then, the engine board performs an abnormality process such as stopping the driving of the actuator, for example. On the other hand, when the count value is less than “45” (“NO”), the process returns to step S2.
When the frequency of the commercial AC power supply 2 is assumed to be 47 Hz (a condition in which the period is the longest), the instantaneous power failure detection value is a value larger than twice the period (1/47 Hz × 2≈43 ms). Is set.

According to the present embodiment described above, the following effects can be obtained.
The instantaneous power failure detection circuit 5 monitors the slope of the voltage waveform of the two phases (R phase and S phase) of the three-phase commercial AC power supply 2, and the state where both of the slopes are less than the threshold value is longer than a predetermined time. If it continues, the instantaneous power failure of the commercial AC power supply 2 was detected. Specifically, the CPU 14a calculates the slopes ΔVr and ΔVs of the voltage waveform for the voltage signals Vr and Vs, performs counting when both ΔVr and ΔVs are less than the threshold value Vth, and one of them is the threshold value. If it is Vth or more, the count value is reset, and when the count value reaches a preset instantaneous power failure detection value (predetermined time), an instantaneous power failure is detected. That is, when an instantaneous power failure occurs, the voltage of each phase gradually decreases due to the influence of the noise removing capacitors 10 to 12, but the slope of the voltage waveform at this time becomes smaller than usual. Therefore, by detecting the instantaneous power failure based on the change in the slope of the voltage waveform as described above, the instantaneous power failure can be detected quickly even when the capacitors 10 to 12 are inserted between the phases. it can.

  The instantaneous power failure detection circuit 5 also monitors the potential difference between the two phases (R phase and S phase) of the three-phase commercial AC power supply 2, and the state where the potential difference is less than the threshold value continues for a predetermined time or more. Even when the condition to do so is satisfied, an instantaneous power failure of the commercial AC power supply 2 is detected. Specifically, the CPU 14a also calculates a data difference A at the same sampling timing for the voltage signals Vr and Vs, performs the above counting even when the difference A is less than the threshold value Vth, and sets the threshold value Vth. If it is above, the count value is reset. That is, when an instantaneous power failure occurs, there is almost no potential difference between the phases. Thus, by monitoring the potential difference between the two phases as well, the instantaneous power failure can be detected more reliably.

Furthermore, since the predetermined time (instantaneous power failure detection value) is set to 45 ms (count value “45”) that is two cycles or more of the power cycle of the commercial AC power supply 2, temporary power fluctuation due to the influence of noise or the like is caused. It is possible to reliably detect an instantaneous power failure by eliminating the erroneous detection based on it.
And since the control part 14 outputs the instantaneous power failure detection signal Sa to an engine board immediately after detecting an instantaneous power failure as mentioned above, each process after an instantaneous power failure is performed in an engine board without a delay. It becomes possible.

The present invention is not limited to the embodiments described above and shown in the drawings, and the following modifications or expansions are possible.
The sampling intervals of the voltage signals Vr and Vs and the threshold value Vth can be appropriately changed according to the power supply conditions such as the voltage and frequency of the commercial AC power supply 2 and superimposed noise, and the detection accuracy of the instantaneous power failure.

The predetermined time for detecting the instantaneous power failure may be less than two AC power supply cycles.
The determination of the instantaneous power failure state based on the difference A between the voltage signals Vr and Vs at the same detection timing may be provided according to the state of the power source to be used.
You may apply to what uses the alternating current power supply of single phase 200V or 100V.
The power supply device 1 is not limited to supplying power to an industrial robot, but may be one that supplies power to other electric and electronic devices.

1 shows an embodiment of the present invention, and is an electrical configuration diagram of a power supply device. The figure which shows the waveform of the voltage signals Vr and Vs Flow chart showing control contents during instantaneous power failure detection processing

Explanation of symbols

  In the drawings, 1 is a power supply device, 2 is a commercial AC power supply (three-phase AC power supply), 4 is a DC power supply circuit, 5 is an instantaneous power failure detection circuit (instantaneous power failure detection means), 9r, 9s, and 9t are AC power wires. -12 is a capacitor | condenser, 14 shows a control part (change amount calculation means, count means).

Claims (5)

In a power supply device comprising a DC power supply circuit that rectifies AC power supplied from a three-phase AC power supply via an AC power supply line into a DC, and a capacitor inserted between the AC power supply lines,
An instantaneous power failure detection means for monitoring an instantaneous power failure of the AC power supply when monitoring a slope of a voltage waveform for any two phases of the three phases, and when both slopes are less than a threshold value for a predetermined time or longer. A power supply apparatus comprising:   The instantaneous power failure detection means also monitors the voltage difference between the two phases, and even if the condition that the voltage difference is less than a threshold value continues for the predetermined time or longer is satisfied, the AC power supply may be instantaneously interrupted. The power supply device according to claim 1, wherein the power supply device is detected.   The power supply apparatus according to claim 1 or 2, wherein the predetermined time is set to two cycles or more of the AC power supply cycle. The instantaneous power failure detection means detects the voltage level of each phase every predetermined period,
A change amount calculating means for calculating a change amount between the current detection value and the past detection value for each phase;
Counting means for counting when the change amount of each phase voltage calculated by the change amount calculation means is less than the threshold value, and resetting the count value when either one is equal to or greater than the threshold value. ,
The power supply device according to any one of claims 1 to 3, wherein the instantaneous power failure is detected when a count value of the counting means reaches a preset detection value.   The counting means obtains a difference in voltage detection values between the phases at the same detection timing, and counts even when a condition that the difference is less than a threshold is satisfied. 5. The power supply device according to claim 4, wherein the count value is reset if the threshold value is exceeded.

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