Rectifier

Abstract

To provide a rectifier that can monitor the state of a circuit element.SOLUTION: A rectifier 1 includes a DC voltage detection unit 6 that detects a DC voltage of a smoothing capacitor 4, an AC voltage detection unit 7 that detects an AC voltage of an AC power supply 10, a PWM control unit 81 that controls a main circuit unit 3, a circuit control unit 82 that controls a switch 2 and a charging circuit 5, and an abnormality determination unit 83 that determines an abnormality in the switch 2, the charging circuit 5, and the main circuit unit 3 on the basis of the DC voltage detected by the DC voltage detection unit 6 and the AC voltage detected by the AC voltage detection unit 7.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rectifier. [Background technology]

[0002] Conventionally, a rectifier used for motor control supplies power to itself by controlling a switch, and the rectifier includes circuit elements such as a power circuit having a switching element and a diode, and a charging circuit for charging an electrolytic capacitor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-216018 A Summary of the Invention [Problem to be solved by the invention]

[0004] If each circuit element of such a rectifier is not controlled normally or if the state of the circuit element cannot be monitored, an unexpected large current or surge voltage may occur, which may cause further damage to the circuit elements and may also cause damage to the inverter circuit connected to the rectifier, etc. Therefore, a rectifier that can monitor the state of the circuit elements is desired. [Means for solving the problem]

[0005] A rectifier according to one embodiment of the present disclosure is a rectifier that converts AC power supplied from an AC power source into DC power, and includes a switch that supplies AC power from the AC power source, a main circuit unit having a switching element and a diode connected in parallel to each of the switching elements, a smoothing capacitor that smoothes the DC voltage output from the main circuit unit, a charging circuit for charging the smoothing capacitor, a DC voltage detection unit that detects the DC voltage of the smoothing capacitor, an AC voltage detection unit that detects the AC voltage of the AC power source, a PWM control unit that controls the main circuit unit, a circuit control unit that controls the switch and the charging circuit, and an abnormality determination unit that determines an abnormality in the switch, the charging circuit, and the main circuit unit based on the DC voltage detected by the DC voltage detection unit and the AC voltage detected by the AC voltage detection unit. Effect of the Invention

[0006] According to the present invention, the state of a circuit element can be monitored. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing a circuit configuration of a rectifier according to the present embodiment. [Diagram 2] FIG. 11 is a diagram showing voltage values ​​when the rectifier is operating normally. [Diagram 3] FIG. 13 is a diagram showing voltage values ​​when the rectifier is operating abnormally. [Figure 4] FIG. 13 is a diagram showing voltage values ​​when the rectifier is operating abnormally. [Diagram 5] 13 is a flowchart showing the process of a rectifier. [Figure 6] 4 is a flowchart showing a switch abnormality determination process. [Figure 7] 5 is a flowchart showing a charging circuit abnormality determination process. [Figure 8] 4 is a flowchart showing a main circuit abnormality determination process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An example of an embodiment of the present invention will now be described. 1 is a diagram showing a circuit configuration of a rectifier 1 according to this embodiment. The rectifier 1 includes a switch 2, a main circuit unit 3, a smoothing capacitor 4, a charging circuit 5, a DC voltage detection unit 6, an AC voltage detection unit 7, and a control unit 8.

[0009] The switch 2 is provided between an AC power source 10 and the main circuit unit 3, and supplies AC power from the AC power source 10. The switch 2 performs switching to connect or disconnect the AC power source 10 and the main circuit unit 3. The switching is performed based on a control signal from the control unit 8. In addition, a reactor 9 may be provided between the switch 2 and the main circuit unit 3.

[0010] The main circuit unit 3 is a converter that converts AC power into DC power. The main circuit unit 3 has six semiconductor switching elements and six diodes connected in parallel to each of the semiconductor switching elements. The semiconductor switching elements are switched on and off based on a control signal from the control unit 8. The semiconductor switching elements may be, for example, IGBTs (Insulated Gate Bipolar Transistors).

[0011] The smoothing capacitor 4 smoothes the DC voltage output from the main circuit unit 3. The charging circuit 5 charges the smoothing capacitor 4. The charging circuit 5 has a switching element, a diode, and a resistor. The switching element may be, for example, a thyristor, a relay circuit, or the like. The DC voltage detection unit 6 detects the DC voltage of the smoothing capacitor 4, and notifies the control unit 8 of the detected DC voltage value.

[0012] The AC voltage detection unit 7 detects the AC voltage of the AC power supply 10, and notifies the control unit 8 of the detected AC power value. The control unit 8 includes a PWM control unit 81, a circuit control unit 82, and an abnormality determination unit 83.

[0013] The PWM control unit 81 generates, for example, a PWM (Pulse Width Modulation) control signal and controls the switching of the main circuit unit 3. The PWM control unit 81 controls the switching of the main circuit unit 3 so as to boost a DC voltage to a predetermined value, for example.

[0014] The circuit control unit 82 controls the opening and closing of the switch 2. The circuit control unit 82 also controls the switching elements of the charging circuit 5.

[0015] The abnormality determination unit 83 determines whether or not there is an abnormality in the switch 2, the charging circuit 5, and the main circuit unit 3 based on the DC voltage detected by the DC voltage detection unit 6 and the AC voltage detected by the AC voltage detection unit 7.

[0016] Specifically, when the circuit control unit 82 controls the switch 2 to be turned OFF and the DC voltage detected by the DC voltage detection unit 6 is equal to or higher than a first voltage value, the abnormality determination unit 83 determines that the switch 2 is abnormal. This enables the abnormality determination unit 83 to determine whether the smoothing capacitor 4 is completely discharged.

[0017] Furthermore, when the circuit control unit 82 controls the switch 2 to be ON and the AC voltage detected by the AC voltage detection unit 7 is equal to or higher than the second voltage value, the abnormality determination unit 83 calculates a charging time constant when the smoothing capacitor 4 is charged by the charging circuit 5. When the charging time constant of the smoothing capacitor 4 is not within a predetermined range indicating normal operation of the charging circuit 5, the abnormality determination unit 83 determines that the charging circuit 5 is abnormal. Here, the predetermined range includes the value of the charging time constant when the smoothing capacitor 4 is operating normally.

[0018] Here, in calculating the charging time constant, if the capacitance of the smoothing capacitor 4 is C, the resistance of the charging circuit 5 is R, the input voltage of the AC power supply 10 is E, and the base of the natural logarithm is e, then the equivalent circuit including the AC power supply 10, the smoothing capacitor 4, and the charging circuit 5 will be an RC series circuit. Note that in this equivalent circuit, reactors, power supply impedance, etc. are omitted for simplicity. The circuit equation of the equivalent circuit is R dq / dt+1 / C q=E The current ic flowing through the resistor R is expressed as follows: ic=dq / dt=E / R·e -(1 / CR)t The voltage of the smoothing capacitor 4 is expressed as follows: Vdc = E(1-e -(1 / CR)t ) Therefore, from these equations, the charging time constant τ = CR. Furthermore, the predetermined range may be selected, for example, from a value that is τ / 2, where τ is a charging time constant.

[0019] Furthermore, when the main circuit unit 3 is controlled by the PWM control unit 81, the abnormality determination unit 83 determines that the main circuit unit 3 is abnormal if the DC voltage detected by the DC voltage detection unit 6 is less than a third voltage value indicating normal operation of the main circuit unit 3. For example, when the DC voltage is boosted by the main circuit unit 3, the third voltage value includes a voltage value that is intended to be boosted by the main circuit unit 3.

[0020] Furthermore, the PWM control unit 81, the circuit control unit 82, and the abnormality determination unit 83 perform sequence control on the switch 2, the charging circuit 5, and the main circuit unit 3. That is, the PWM control unit 81, the circuit control unit 82, and the abnormality determination unit 83 perform control on the switch 2, the charging circuit 5, and the main circuit unit 3 in that order.

[0021] Furthermore, when the abnormality determination unit 83 determines that any one of the switch 2, the main circuit unit 3, and the charging circuit 5 is abnormal, the control unit 8 performs an abnormality notification process for notifying the user of the abnormality.

[0022] Fig. 2 is a diagram showing voltage values ​​when the rectifier 1 is operating normally. Figs. 3 and 4 are diagrams showing voltage values ​​when the rectifier is operating abnormally. In Figs. 2 to 4, Vac is the AC voltage detected by the AC voltage detection unit 7 and is represented by a sine wave. Vdc is the DC voltage detected by the DC voltage detection unit 6.

[0023] 2, when the rectifier 1 is normally controlled, when the switch 2 is turned ON under the control of the circuit control unit 82, the DC voltage Vdc gradually rises from 0 V. When the switching element of the charging circuit 5 is turned ON under the control of the circuit control unit 82, the smoothing capacitor 4 is charged by the charging circuit 5, and the DC voltage Vdc becomes approximately equal to the amplitude of the AC voltage Vac.

[0024] Furthermore, when the PWM control of the main circuit unit 3 is turned ON (the IGBT of the main circuit unit 3 is turned ON) by the control of the PWM control unit 81, the DC voltage Vdc is boosted to a value higher than the amplitude of the sine wave of the AC voltage Vac.

[0025] 3, when the switch 2 is abnormal (for example, the switch 2 is welded), the DC voltage Vdc has a value substantially equal to the amplitude of the sine wave of the AC voltage Vac before the switch 2 is turned on. In other words, the smoothing capacitor 4 is charged before the switch 2 is turned on.

[0026] In order to determine such an abnormality, the abnormality determination unit 83 determines that the switch 2 is abnormal when the circuit control unit 82 controls the switch 2 to be turned OFF and the DC voltage detected by the DC voltage detection unit 6 is equal to or greater than the first voltage value V1.

[0027] 4, if the charging circuit 5 is abnormal (for example, the resistor in the charging circuit 5 is broken), the DC voltage Vdc rises rapidly after the switch 2 is turned ON. That is, the smoothing capacitor 4 is charged rapidly after the switch 2 is turned ON, and the charging circuit 5 is not operating normally.

[0028] In order to determine such an abnormality, the abnormality determination unit 83 determines that the charging circuit 5 is abnormal if the charging time constant of the smoothing capacitor 4 is not within a predetermined range.

[0029] FIG. 5 is a flowchart showing the process of the rectifier. In step S1, the rectifier 1 executes a switch abnormality determination process for determining whether the switch 2 has an abnormality. In step S2, the rectifier 1 executes a charging circuit abnormality determination process for determining whether the charging circuit 5 has an abnormality. In step S3, the rectifier 1 executes a main circuit abnormality determination process for determining whether or not the main circuit unit 3 has an abnormality. The switch abnormality determination process, the charging circuit abnormality determination process, and the main circuit abnormality determination process will be described below with reference to FIGS. 6 to 8. FIG.

[0030] FIG. 6 is a flowchart showing the switch abnormality determination process. In step S11, the circuit control section 82 turns the switch 2 off. In step S12, the abnormality determination unit 83 waits for a certain time T1, for example, using a timer built into the control unit 8. This process causes the smoothing capacitor 4 to be completely discharged.

[0031] In step S13, the abnormality determination unit 83 determines whether the DC voltage Vdc is equal to or greater than the first voltage value V1. If the DC voltage Vdc is equal to or greater than the first voltage value V1 (YES), the process proceeds to step S14, and if the DC voltage Vdc is smaller than the first voltage value V1 (NO), the process proceeds to step S17. In this way, the abnormality determination unit 83 determines whether the smoothing capacitor 4 has been completely discharged by the processes of steps S12 and S13.

[0032] In step S14, the circuit control unit 82 turns the switch 2 ON. In step S15, the abnormality determination unit 83 waits for a certain period of time T2 using, for example, a timer.

[0033] In step S16, the abnormality determination unit 83 determines whether or not the AC voltage Vac is equal to or greater than the second voltage value V2. If the AC voltage Vac is equal to or greater than the second voltage value V2 (YES), the process proceeds to step S2. If the AC voltage Vac is less than the second voltage value V2 (NO), the process proceeds to step S17. This allows the abnormality determination unit 83 to determine an abnormality when the switch 2 cannot be turned ON.

[0034] In step S17, the abnormality determination unit 83 determines that the switch 2 is abnormal, executes a process to notify the abnormality, and then ends the process.

[0035] FIG. 7 is a flowchart showing the charging circuit abnormality determination process. In step S21, the circuit control unit 82 turns the switching element of the charging circuit 5 off.

[0036] In step S22, the abnormality determination unit 83 calculates the charging time constant of the smoothing capacitor 4, and determines whether or not the charging time constant of the smoothing capacitor 4 is within the range from threshold C1 to threshold C2. If the charging time constant is within the range from threshold C1 to threshold C2 (YES), the process proceeds to step S23. If the charging time constant is not within the range from threshold C1 to threshold C2 (NO), the process proceeds to step S25. This process makes it possible to determine whether or not a direct current is passing through the resistor of the charging circuit 5. Here, the range from threshold C1 to threshold C2 corresponds to a predetermined range indicating normal operation of the charging circuit 5.

[0037] In step S23, the circuit control unit 82 turns the switching element of the charging circuit 5 ON. In step S24, the abnormality determination unit 83 calculates the charging time constant of the smoothing capacitor 4, and determines whether or not the charging time constant of the smoothing capacitor 4 is within the range from threshold C3 to threshold C4. If the charging time constant is within the range from threshold C3 to threshold C4 (YES), the process proceeds to step S3. If the charging time constant is not within the range from threshold C3 to threshold C4 (NO), the process proceeds to step S25. This process enables the rectifier 1 to determine whether or not the charging circuit 5 is short-circuited. Here, the range from threshold C3 to threshold C4 corresponds to a predetermined range indicating normal operation of the charging circuit 5.

[0038] In step S25, the abnormality determination unit 83 determines that the charging circuit 5 is abnormal, and executes a process to notify the user of the abnormality, and then ends the process.

[0039] FIG. 8 is a flowchart showing the main circuit abnormality determination process. In step S31, the PWM control unit 81 generates a PWM control signal and controls the switching of the main circuit unit 3.

[0040] In step S32, the abnormality determination unit 83 determines whether the DC voltage Vdc is equal to or greater than the third voltage value V3. If the DC voltage Vdc is equal to or greater than the third voltage value V3 (YES), the process proceeds to step S33. If the DC voltage Vdc is less than the third voltage value V3 (NO), the process proceeds to step S34.

[0041] In step S33, since there are no abnormalities in the switch 2, the main circuit unit 3, and the charging circuit 5, the control unit 8 sends a ready signal indicating that the rectifier 1 has started up normally to the inverter circuit, converter circuit, etc. connected to the rectifier 1.

[0042] In step S34, the abnormality determination unit 83 determines that the main circuit unit 3 is abnormal, and executes a process to notify the user of the abnormality, and then ends the process.

[0043] According to this embodiment, the rectifier 1 includes a DC voltage detection unit 6 that detects the DC voltage of the smoothing capacitor 4, an AC voltage detection unit 7 that detects the AC voltage of the AC power source 10, a PWM control unit 81 that controls the main circuit unit 3, a circuit control unit 82 that controls the switch 2 and the charging circuit 5, and an abnormality determination unit 83 that determines abnormalities in the switch 2, the charging circuit 5, and the main circuit unit 3 based on the DC voltage detected by the DC voltage detection unit 6 and the AC voltage detected by the AC voltage detection unit 7.

[0044] This allows the rectifier 1 to collectively determine abnormalities in the switch 2, the charging circuit 5, and the main circuit section 3, rather than individually determining abnormalities in the switch 2, the charging circuit 5, and the main circuit section 3. Therefore, the rectifier 1 can appropriately monitor the states of the circuit elements.

[0045] Furthermore, the abnormality determination unit 83 determines that the switch 2 is abnormal when the circuit control unit 82 controls the switch 2 to be turned OFF and the DC voltage detected by the DC voltage detection unit 6 is equal to or greater than the first voltage value V1. This enables the rectifier 1 to appropriately determine whether the switch 2 is abnormal.

[0046] In addition, the abnormality determination unit 83 calculates the charging time constant of the smoothing capacitor 4 when it is charged by the charging circuit 5, and determines that the charging circuit 5 is abnormal if the charging time constant of the smoothing capacitor 4 is not within a predetermined range. This allows the rectifier 1 to appropriately determine whether or not the charging circuit 5 is abnormal.

[0047] Furthermore, when the main circuit unit 3 is controlled by the PWM control unit 81, the abnormality determination unit 83 determines that the main circuit unit 3 is abnormal if the DC voltage detected by the DC voltage detection unit 6 is less than the second voltage value V2. This allows the rectifier 1 to appropriately determine whether or not the main circuit unit 3 is abnormal.

[0048] In addition, the PWM control unit 81, the circuit control unit 82, and the abnormality determination unit 83 perform sequence control on the switch 2, the charging circuit 5, and the main circuit unit 3. This allows the rectifier 1 to collectively determine abnormalities according to the order of operation of the switch 2, the charging circuit 5, and the main circuit unit 3.

[0049] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. Furthermore, the effects described in the present embodiment are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the present embodiment. [Explanation of symbols]

[0050] 1 rectifier 2 Switchgear 3 Main circuit section 4 Smoothing capacitors 5 Charging circuit 6 DC voltage detection section 7 AC voltage detection section 8. Control Unit 9. Reactor 10 AC power supply 81 PWM control unit 82 Circuit control section 83 Abnormality determination section

Claims

[Claim 1] A rectifier that converts AC power supplied from an AC power source into DC power, A switch for supplying AC power from the AC power source; a main circuit section having switching elements and diodes connected in parallel to each of the switching elements; a smoothing capacitor that smoothes the DC voltage output from the main circuit unit; a charging circuit for charging the smoothing capacitor; A DC voltage detection unit that detects a DC voltage of the smoothing capacitor; an AC voltage detection unit that detects an AC voltage of the AC power supply; A PWM control unit that controls the main circuit unit; A circuit control unit that controls the switch and the charging circuit; an abnormality determination unit that determines an abnormality in the switch, the charging circuit, and the main circuit unit based on the DC voltage detected by the DC voltage detection unit and the AC voltage detected by the AC voltage detection unit; Equipped with The abnormality determination unit When the circuit control unit controls the switch to be turned off and the DC voltage detected by the DC voltage detection unit is equal to or higher than a first voltage value, it is determined that the switch is abnormal; when the circuit control unit controls the switch to be ON and the AC voltage detected by the AC voltage detection unit is equal to or higher than a second voltage value, a charging time constant when the smoothing capacitor is charged by the charging circuit is calculated, and when the charging time constant of the smoothing capacitor is not within a predetermined range, it is determined that the charging circuit is abnormal; when the main circuit unit is controlled by the PWM control unit, if the DC voltage detected by the DC voltage detection unit is less than a third voltage value, it is determined that the main circuit unit is abnormal; The PWM control unit, the circuit control unit, and the abnormality determination unit perform sequence control on the switch, the charging circuit, and the main circuit unit to collectively determine abnormalities according to the operation sequence of the switch, the charging circuit, and the main circuit unit. rectifier.

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