JP5617306B2 - Overvoltage protection device - Google Patents

Description

  The present invention relates to an overvoltage protection device that protects a capacitor and a power converter in a driving device that drives a synchronous machine from an overvoltage caused by a no-load induced voltage generated in the synchronous machine during regeneration.

When a ground fault or short circuit occurs in the induction machine during operation of the induction machine and the power converter (inverter) stops for protection, the no-load induced voltage of the induction machine becomes larger than the DC bus voltage Thus, when the regenerative energy generated in the induction machine flows into the power converter side and a voltage exceeding these breakdown voltages is applied to the power converter and the DC side capacitor, the power converter and the capacitor are destroyed.
For this reason, in the conventional overvoltage protection device, when the overvoltage generated in the secondary circuit due to a ground fault or short circuit exceeds a preset level, the overvoltage detection circuit detects this and gives an ignition pulse to the thyristor. It was ignited by an arc pulse to short-circuit the induction machine wires and suppress overvoltage. (See Patent Document 1)

JP-A-9-149545 ([0002] to [0008], FIG. 9)

  The conventional overvoltage protection device is effective when a ground fault or short circuit occurs in the induction machine. However, when the load is not an induction machine but a synchronous machine such as a permanent magnet field synchronous motor (PM motor), The power converter stops due to a cause other than ground fault or short circuit of the induction machine, such as for protection, and the no-load induced voltage of the synchronous machine becomes larger than the DC bus voltage, so that the regenerative energy generated in the synchronous machine is reduced. When flowing into the power converter, if the DC bus voltage rises and exceeds the breakdown voltage of the power converter or capacitor, there is a problem that the power converter or capacitor may be destroyed.

For example, if the synchronous machine is a permanent magnet synchronous machine that creates a magnetic field with a permanent magnet attached to the rotor, the magnetic flux generated by the permanent magnet is constant, and is proportional to the product of the magnetic flux density and the rotational speed of the synchronous machine. No-load induced voltage is generated. This no-load induced voltage has a characteristic proportional to the rotational frequency of the synchronous machine.
On the other hand, since the power converter cannot generate a voltage higher than the DC voltage of the input DC power supply, in the region where the no-load induced voltage exceeds the maximum output voltage of the power converter, the magnetic flux generated by the permanent magnet is generated. The power converter performs so-called field weakening control so that a magnetic flux that cancels out is generated in the armature winding, and the operation up to the high-speed rotation region is performed.
However, when the operation of the power converter is stopped, the synchronous machine cannot be controlled. Therefore, when the no-load induced voltage becomes larger than the voltage of the DC power supply, a current flows from the synchronous machine to the capacitor, and the capacitor and power A voltage value equivalent to the no-load induced voltage is applied to the converter, and if the applied voltage exceeds the breakdown voltage of the capacitor and the power converter, the capacitor and the power converter are destroyed. .

Further, in the conventional overvoltage protection device, the voltage of the DC-side capacitor rises due to the inflow of regenerative energy. Therefore, in this state, the power converter cannot be quickly returned (restarted) from the stopped state. There was a problem.
Further, in the conventional overvoltage protection device, a switching element (in the previous example, a thyristor is used) that short-circuits the lines of the induction machine to prevent overvoltage is required for three phases, resulting in a large number of parts and cost. There was a problem of becoming high.

  The present invention has been made to solve the above-described problems, and prevents damage to a power converter and a capacitor in which regenerative energy is accumulated due to a no-load induced voltage generated in a synchronous machine when the power converter is stopped. Thus, the power converter can be promptly returned (restarted) from the stopped state, and a low-cost overvoltage protection device is obtained.

An overvoltage protection device according to the present invention includes a DC power source that is a power source for driving a synchronous machine, a power converter that converts a DC current output from the DC power source into an AC current and outputs the AC current to the synchronous machine, Regenerative energy storage means for storing regenerative energy generated in the synchronous machine, connected in parallel to the DC power source and the power converter, respectively, and an overvoltage protection device for a synchronous machine drive device comprising: A regenerative power suppressor connected to the synchronous machine and the power converter, detecting a no-load induced voltage due to regenerative energy generated in the synchronous machine, and suppressing the regenerative energy based on the no-load induced voltage; The regenerative energy storage means is connected in parallel to the regenerative energy storage means and follows the instruction based on the no-load induced voltage from the regenerative power suppressor. Discharge means for discharging the regenerative power suppressor, wherein the regenerative power suppressor generates the regenerative energy when the no-load induced voltage reaches a regenerative energy suppression start voltage value that is less than a breakdown voltage value of the regenerative energy storage means. An operation to suppress is started, and when the no-load induced voltage becomes a regenerative energy suppression end voltage value smaller than the regenerative energy suppression start voltage value, the operation to suppress the regenerative energy is ended, and the discharging means An instruction based on a no-load induced voltage is issued, the discharge means is operated after the regenerative energy suppression operation of the regenerative power suppressor is started, the regenerative energy is suppressed by short-circuiting the lines of the synchronous machine, and the discharge means, connected in parallel with the DC power supply, wherein the no-load induced voltage from the regenerative energy suppression start voltage value Remained until the power converter operable voltage value the force transducer are operable, and until said shorting means reaches a temperature that enables operation, the interrupts power supply from the DC power source, the no-load While the induced voltage changes from the regenerative energy suppression end voltage value to the power converter operable voltage value, the regenerative energy storage means is discharged.

According to the overvoltage protection device of the present invention, since the stop state of the power converter is detected and the regenerative energy is suppressed according to the voltage value of the no-load induced voltage generated by the synchronous machine, the no-load dielectric generated by the synchronous machine Regenerative energy storage means such as a power converter and a capacitor can be protected from overvoltage due to voltage.
Also, after the regenerative energy is suppressed by short-circuiting the lines of the synchronous machine, when the no-load dielectric voltage drops, the short-circuit is stopped and the regenerative energy storage means that stores the regenerative energy is discharged, so the power converter is stopped. It is possible to quickly return (restart) from the state.
Furthermore, the line of the synchronous machine can be short-circuited by one switching element, and the regenerative energy storage means can be discharged without using a means for detecting the voltage of the regenerative energy storage means such as a capacitor. Can be simplified and the cost can be reduced.

It is a block diagram which shows the overvoltage protection apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the short circuit control means which concerns on Embodiment 1 of this invention. It is a timing chart figure which shows operation | movement of the overvoltage protection apparatus which concerns on Embodiment 1 of this invention. It is a simulation result of operation | movement of the overvoltage protection apparatus which concerns on Embodiment 1 of this invention. It is a block diagram which shows the overvoltage protection apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the short circuit control means which concerns on Embodiment 2 of this invention. It is a timing chart figure which shows operation | movement of the overvoltage protection apparatus which concerns on Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram illustrating an overvoltage protection device according to Embodiment 1 of the present invention. In FIG. 1, the synchronous machine drive system to which the overvoltage protection device of this embodiment is connected converts the direct current output from the direct current power source 4 into an alternating current by the power converter 2 connected in parallel with the direct current power source 4. The synchronous machine 1 is driven by the alternating current. The power converter 2 includes a plurality of switching elements including diodes. Between the DC power source 4 and the power converter 2, regenerative energy storage means 3 such as a capacitor connected in parallel with each other and storing regenerative energy is provided. The overvoltage protection device 10 is connected between the power converter 2 and the synchronous machine 1, and is connected between the regenerative power suppressor 5 that suppresses regenerative energy generated in the synchronous machine 1, the DC power supply 4, and the regenerative energy storage unit 3. And discharge means 9 connected in parallel to these for discharging the charge stored in the regenerative energy storage means 3. Here, it is assumed that the maximum value of the no-load induced voltage of the synchronous machine 1 is larger than the DC voltage of the DC power supply 4.

  The regenerative power suppressor 5 will be described. In FIG. 1, the regenerative power suppressor 5 includes a voltage detection unit 6, a short circuit unit 7, and a short circuit control unit 8, which will be described later, and a three-phase line (U, V, W phase) and the N side of the power converter 2 are respectively connected. The voltage detection means 6 is composed of three diodes connected to the U, V and W phase three-phase lines of the synchronous machine 1. The output sides of the three diodes are connected to each other. The voltage detection means 6 detects the value of the no-load induced voltage of the synchronous machine 1 by performing half-wave rectification on the three-phase line of the synchronous machine 1 using the three diodes having the above-described configuration. The short-circuit means 7 is composed of one switching element, and one of the switching elements is connected to the N side of the power converter 2 and the other is connected to the output side of the three diodes of the voltage detection means 6. By operating this switching element, the lines of the synchronous machine 1 are short-circuited. The short-circuit control means 8 is connected in parallel with the short-circuit means 7. That is, one is connected to the output side of the three diodes of the voltage detection means 6, and the other is connected to the N side of the power converter 2. Therefore, the no-load induced voltage detected by the voltage detection means 6 is input to the short-circuit control means 8. The short-circuit control means 8 short-circuits the lines of the synchronous machine 1 when the no-load induced voltage value detected by the voltage detection means 6 falls within a predetermined range below the breakdown voltage of the regenerative energy storage means 3. The operation of the short-circuit means 7 is controlled.

  The discharge means 9 will be described. In FIG. 1, the discharge means 9 includes a discharge switching means 9a, a discharge resistor 9b, and an opening means 9c, which will be described later, and these are connected in series. One of the discharge switching means 9a is connected to one side of the regenerative energy storage means 3, and the other is connected to the discharge resistor 9b. When the no-load induced voltage value detected by the voltage detection means 6 falls within a predetermined range below the breakdown voltage of the regenerative energy storage means 3, the discharge switching means 9a receives an instruction from the short-circuit control means 8 and turns on Operate (connect). The discharge resistor 9b is connected in series between the discharge switching unit 9a and the regenerative energy storage unit 3, and when the discharge switching unit 9a is closed, the regenerative energy storage unit 3, the discharge resistor 9b, and the discharge The switching means 9a becomes a closed circuit, and the energy discharged by the regenerative energy storage means 3 is converted into heat and consumed by the discharging resistor 9b. One of the opening means 9c is connected to one side of the DC power supply 4 (+ side in the present embodiment), and the other is connected to the discharging resistor 9b. The opening means 9c receives an instruction from the short-circuit control means 8 when the no-load induced voltage value detected by the voltage detection means 6 falls within a predetermined range below the breakdown voltage of the regenerative energy storage means 3, and is turned on (opened). The power supply from the DC power source 4 is cut off.

  The short circuit control means 8 will be described. FIG. 2 shows the configuration of the short-circuit control means 8. In FIG. 2, the no-load induced voltage value Vm of the synchronous machine 1 detected by the voltage detection means 6 is input to the comparison means 8a, comparison means 8b, and comparison means 8c. The comparison unit 8a, the comparison unit 8b, and the comparison unit 8c include a regenerative energy suppression start voltage value V1 for starting a regenerative energy suppression operation and a regenerative energy suppression end voltage value V2 for ending the regenerative energy suppression operation, respectively. In addition, a power converter operable voltage value V3 for enabling the power converter to operate is set in advance, and a comparison operation between the preset voltage value and the no-load induced voltage value Vm is performed. Here, the regenerative energy suppression start voltage value V1, the regenerative energy suppression end voltage value V2, and the power converter operable voltage value V3 have a relationship of V1> V2> V3, and all are breakdown voltages of the regenerative energy storage means 3. Is less than. Although the regenerative energy suppression start voltage value V1 is equal to or higher than the DC power supply voltage value, there is no problem even if the regenerative energy suppression end voltage value V2 and the power converter operable voltage value V3 are equal to or lower than the DC power supply voltage value. The comparison unit 8a outputs an ON signal when the no-load induced voltage value Vm is equal to or higher than the regenerative energy suppression start voltage value V1. The comparison unit 8b outputs an ON signal when the no-load induced voltage value Vm is equal to or higher than the regenerative energy suppression end voltage value V2. The comparison unit 8c outputs an ON signal when the no-load induced voltage value Vm is larger than the power converter operable voltage value V3. Latch means 8g is provided on the output side of the comparison means 8a and latches (holds) the ON signal of the comparison means 8a. Further, an inversion means 8f for inverting the output signal of the comparison means 8c is provided on the output side of the comparison means 8c, and the latch of the latch means 8g is released by the ON output of the inversion means 8f. Further, a logical product unit 8d that calculates the logical product of the output of the comparison unit 8a and the output of the comparison unit 8b, and the logical product of the inversion of the output of the comparison unit 8a and the output of the comparison unit 8b and the output of the comparison unit 8c. A logical product means 8e is provided. The short-circuit control means 8 discharges the output signal of the logical product means 8e to the open-circuit means 9c using the output signal of the comparison means 8a as the open control signal OS, the output signal of the logical product means 8d to the short-circuit means 7 as the short-circuit control signal SCS. The control signal GS is output to the discharge switching means 9a.

Next, the operation of the overvoltage protection device according to Embodiment 1 of the present invention will be described. FIG. 3 is a timing chart showing the operation of the overvoltage protection device according to the present embodiment. In FIG. 3, when the current converter 2 is stopped from the operating state for some reason while the synchronous machine 1 is driven by the output of the current converter 2, the current supply to the synchronous machine 1 is cut off. Since 1 is inertia and continues to rotate, regenerative energy is generated in the synchronous machine 1. When the maximum value of the no-load induced voltage generated in the synchronous machine 1 by this regeneration is larger than the voltage value of the DC power supply 4, this regenerative energy flows from the synchronous machine 1 to the power converter 2. The regenerative energy that has flowed into the power converter 2 flows into the regenerative energy storage means 3 via a diode included in each switching element. Since the regenerative energy storage unit 3 stores regenerative energy, the regenerative energy storage unit voltage Vc increases.
Further, since the regenerative energy generated in the synchronous machine 1 also flows into the voltage detection means 6 connected to the three-phase line of the synchronous machine 1, the output voltage of the voltage detection means 6 is also the same value as the regenerative energy storage means voltage Vc. To rise. Here, since the voltage detection circuit 6 performs the three-phase half-wave rectification of the synchronous machine 1 as described above, the output voltage of the voltage detection circuit 6 matches the value Vm of the no-load induced voltage of the synchronous machine 1. Become.
The output of the voltage detection circuit 6 is input to the short-circuit control means 8 via one side of the short-circuit means 7, and as shown in FIG. 2, the output voltage of the voltage detection circuit 6, that is, the no-load induced voltage value Vm is compared with the comparison means 8a. Input to 8b and 8c, respectively.

  At the time t1, in the short-circuit control means 8, the voltage Vm is the power converter operable voltage value V3 (in this embodiment, the power converter operable voltage value V3 is equal to the DC voltage Vdc of the DC power supply 4). .)), An ON signal is output from the comparison means 8c. At this time, since the voltage Vm is V1> V2> Vm> V3, the outputs of the comparison means 8a and 8b are both off.

  Next, when the voltage Vm becomes equal to or higher than the regenerative energy suppression end voltage value V2 at time t2, an ON signal is output from the comparison unit 8b. At this time, since the voltage Vm is V1> Vm ≧ V2> V3, the output of the comparison unit 8c remains on and the output of the comparison unit 8a is off.

Next, when the voltage Vm becomes equal to or higher than the regenerative energy suppression start voltage value V1 at time t3, an ON signal is output from the comparison unit 8a. At this time, since the voltage Vm is Vm ≧ V1>V2> V3, the outputs of the comparison unit 8c and the comparison unit 8b remain on.
When the ON signal is output from the comparison unit 8a, the ON signal of the comparison unit 8a is latched (held) by the latch unit 8g provided on the output side of the comparison unit 8a. Further, the opening control signal OS of the short-circuit control means 8 is turned on when the comparison means 8a is turned on. Further, since ON signals are input to the AND unit 8d from the comparison unit 8a and the comparison unit 8b, the AND unit 8d calculates these logical products and outputs the ON signal as the short circuit control signal SCS of the short circuit control unit 8. To do.

  At time t3, when the opening control signal OS is turned on, the opening means 9c of the discharging means 9 operates to open the connection path between the discharging means 9 and the DC power source 4, and supply power from the DC power source 4. Cut off. Further, when the short-circuit control signal SCS is turned on, the short-circuit means 7 of the regenerative power suppressor 5 operates, and one switching element (for example, thyristor element) constituting the short-circuit means 7 is turned on and the U of the synchronous machine 1 is turned on. The phase, V phase, and W phase lines are short-circuited. Since the three-phase wires of the synchronous machine 1 are short-circuited by one switching element of the short-circuit means 7 based on the no-load induced voltage Vm of the synchronous machine 1 detected by the voltage detection circuit 6 constituted by three diodes, the short-circuit means 7 can be stably short-circuited without repeatedly turning on and off. Due to the short circuit between the three-phase lines of the synchronous machine 1, the brake torque is generated and the rotation of the synchronous machine 1 is decelerated. Therefore, the generation of regenerative energy is suppressed and the no-load induced voltage of the synchronous machine 1 proportional to the rotational speed is reduced. The value Vm decreases. As a result, the output voltage of the voltage detection circuit 6 also decreases.

  Next, when the voltage Vm becomes smaller than the regenerative energy suppression end voltage value V2 at time t4, the output signal of the comparison unit 8b is turned off, so that the short circuit control signal SCS that is the output signal of the AND unit 8d is turned off. The short-circuit means 7 cancels the short-circuit state. Therefore, at time t4, the short-circuit means 7 operates and the period (regenerative energy suppression period) in which the generation of regenerative energy is suppressed by the short-circuit state between the three-phase lines of the synchronous machine 1 ends. That is, the regenerative energy suppression period is from when the voltage Vm exceeds the regenerative energy suppression start voltage value V1 (t3) to when it becomes smaller than the regenerative energy suppression end voltage value V2 (t4).

Further, when the voltage Vm becomes smaller than the regenerative energy suppression end voltage value V2 at time t4, the output of the comparison means 8b is turned off, so that the discharge control signal GS is turned on, and the discharge switching means 9a of the discharge means 9 is turned on. The Since the ON signal of the comparison unit 8a is held by the latch unit 8g, the release control signal OS that is the output signal of the comparison unit 8a is still ON. Therefore, the connection means between the discharge means 9 and the DC power supply 4 is open while the opening means 9c is operating.
Therefore, since the regenerative energy storage unit 3, the discharge resistor 9b, and the discharge switching element 9a are closed, the regenerative energy storage unit 3 is discharged, and the energy stored in the regenerative energy storage unit 3 is heated by the discharge resistor 9b. It is converted and consumed. This discharge reduces the regenerative energy storage means voltage Vc.

  Next, when the voltage Vm becomes equal to or lower than the power converter operable voltage value V3 at time t5, the output signal of the comparison unit 8c is turned off, so that the discharge control signal GS that is the output signal of the AND unit 8e is turned off. The discharge switching means 9a of the discharge means 9 is turned off, and the discharge of the regenerative energy storage means 3 is completed. Accordingly, at time t5, when the discharge switching unit 9a is turned off, the period (discharge period) in which the regenerative energy storage unit 3 discharges and releases the stored energy ends. That is, during the discharge period, when the voltage Vm becomes smaller than the regenerative energy suppression end voltage value V2 that becomes the discharge start voltage value (t4), the power converter operable voltage value V3 that is the discharge end voltage value is less than or equal to V3. Until (t5).

  In the present embodiment, the voltage value at which the regenerative energy suppression operation ends and the voltage value at which discharge starts are both equal to V2, but may be different values.

  Since the power converter operable voltage value V3 is set to a steady voltage value at which the power converter 2 can be activated, the regenerative energy storage means voltage Vc drops to a steady voltage value at which the power converter 2 can be activated due to discharge. It becomes possible to make it.

  At time t5, since the output signal of the comparison means 8c is turned off, the output of the inverting means 8f is turned on, and the latch of the latch means 8g is released by the output, and the output of the comparison means 8a is turned off. Therefore, the open control signal OS which is the output signal of the comparison means 8a is turned off, whereby the open means 9c is closed, the path between the DC power supply 4 and the power converter 2 is connected via the discharge means 9, and the DC power supply The power supply from 4 is restored.

  After time t5, the value Vm of the no-load induced voltage of the synchronous machine 1 and the regenerative energy storage means voltage Vc are both equal to or lower than the power converter operable voltage value V3, so that the power converter 2 is restored (restarted). It is possible to make it.

  In FIG. 4, the result of having confirmed the operation | movement of the overvoltage protection apparatus which concerns on this Embodiment by simulation is shown. In FIG. 4, the rated output of the synchronous machine is 11 kW, and the time t1 to t3 in FIG. 3 and the regenerative energy storage means voltage Vc in a part of the regenerative energy suppression period are shown. From this result, the regenerative energy storage means voltage Vc is regenerated by short-circuiting the three-phase lines of the synchronous machine 1 by the short-circuit means 7 in a state where the no-load induced voltage Vm is rising in the synchronous machine 1 due to regenerative energy. It can be confirmed that the voltage does not rise above the energy suppression start voltage value V1 (here, V1 = 800 V).

According to the overvoltage protection device of the present embodiment, the current converter 2 is stopped from the operating state for some reason, and the regenerative operation of the synchronous machine 1 causes the no-load induced voltage Vm of the synchronous machine 1 and the regenerative energy storage means. When the voltage Vc rises, when the no-load induced voltage Vm becomes equal to or higher than the regenerative energy suppression start voltage value V1 less than the breakdown voltage of the regenerative energy storage means 3, the three-phase lines of the synchronous machine 1 are short-circuited to regenerate energy. By suppressing and reducing the no-load induced voltage Vm, it is possible to protect regenerative energy storage means such as a power converter and a DC side capacitor from overvoltage.
Also, since the no-load induced voltage Vm drops due to a short circuit between the three-phase lines of the synchronous machine 1 and becomes smaller than the regenerative energy suppression end voltage value V2, the voltage of the regenerative energy storage means 3 is within a voltage range in which normal operation is performed. Since the regenerative energy storage means 3 can be discharged until the power converter operable voltage value V3 or less, the power converter 2 can be quickly returned (restarted) from the stop.
Moreover, the switching element which short-circuits between the three-phase lines of the synchronous machine 1 can be comprised by one, and cost reduction can be performed.
Furthermore, the line of the synchronous machine can be short-circuited by one switching element, and the regenerative energy storage means can be discharged without using a means for detecting the voltage of the regenerative energy storage means such as a capacitor. Can be simplified and the cost can be reduced.

Embodiment 2. FIG.
FIG. 5 is a block diagram showing an overvoltage protection device according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to the same part as the structure demonstrated in Embodiment 1, and the description is abbreviate | omitted.
As shown in FIG. 5, the overvoltage protection device according to the second embodiment differs from the overvoltage protection device according to the first embodiment in the short-circuit control means, and in particular, in the method of releasing the latch of the comparison means 8a. The short-circuit control means 8 of the overvoltage protection device according to the first embodiment releases the latch by the ON signal of the inverting means 8f that inverts the output signal of the comparison means 8c, but the short-circuit control of the overvoltage protection device according to the second embodiment. The means 12 starts counting time after the comparison means 8a is turned on, and releases the latch after a predetermined time has elapsed.

  The short circuit control means 12 will be described. FIG. 6 shows the configuration of the short-circuit control means 12. In FIG. 6, the short-circuit control means 8 is different from the short-circuit control means 8 in that there is no inversion means 8f for releasing the latch of the latch means 8g. Instead, the time is counted by the ON output of the comparison means 8a on the output side of the comparison means 8a. The timer 11a to be started is compared with the preset stop set time ST and the time counted by the timer 11a, and the latch is released when the time counted by the timer 11a becomes equal to or greater than the stop set time ST. The time comparison means 11b for outputting the above signal to the latch means 8g is provided.

Next, the operation of the overvoltage protection device according to Embodiment 2 of the present invention will be described.
FIG. 7 is a timing chart showing the operation of the overvoltage protection device according to the present embodiment.
In FIG. 7, the operation from the time when the current converter 2 is stopped until the time t5 is the same as that of the overvoltage protection device according to the first embodiment except for the operations of the timer 11a and the time comparison unit 11b. The operation of the time comparison unit 11b will be described.

When the voltage Vm becomes equal to or higher than the regenerative energy suppression start voltage value V1 at time t3, an ON signal is output from the comparison unit 8a. At this time, since the voltage Vm is Vm ≧ V1>V2> V3, the outputs of the comparison unit 8c and the comparison unit 8b remain on.
When the ON signal is output from the comparison unit 8a, the ON signal of the comparison unit 8a is latched (held) by the latch unit 8g provided on the output side of the comparison unit 8a. The ON output of the comparison means 8a is input to the timer 11a, and the timer 11a starts counting time. The timer 11a continuously outputs the counted time to the time comparison unit 11b. The time comparison unit 11b compares the time counted by the timer 11a with a preset stop set time ST. When the time counted by the timer 11a is less than or equal to the preset stop set time ST, an off signal is output to the latch means 8g.

  Next, even at time t5, even if the output voltage Vm of the voltage detection circuit 6 drops below the power converter operable voltage value V3 and the discharge of the regenerative energy storage means 3 ends, the latch of the comparison means 8a is immediately latched. (Hold) is not released. By continuing the ON output of the opening control signal OS, the opening operation of the opening means 9c is continued, the path to the DC power supply 4 is opened, and the power supply from the DC power supply 4 is cut off. As a result, as in the first embodiment, the power conversion is performed immediately after the no-load induced voltage value Vm of the synchronous machine 1 and the voltage Vc of the regenerative energy storage means 3 become equal to or lower than the power converter operable voltage value V3. The device 2 cannot be restored (restarted). In the present embodiment, after the ON signal of the comparison unit 8a is output, that is, from when the voltage Vm becomes equal to or higher than the regenerative energy suppression start voltage value V1, until the stop set time ST elapses, the power converter 2 Remains stopped and cannot be restarted.

  When the time t5 has elapsed (that is, the regenerative energy suppression period and the discharge period have elapsed), and the time counted by the timer 11a exceeds the predetermined stop set time ST at time t6 (that is, ST = t6-t3). ), The ON signal is output from the time comparison means 11b to the latch means 8g, and the latch (hold) of the comparison means 8a is released. When the latch (holding) of the comparison unit 8a is released, the open control signal OS is turned off, the open unit 9c is closed, the path to the DC power supply 4 is connected, and the power supply from the DC power supply 4 is restored. From the above, the power converter 2 can be activated.

In the overvoltage protection device according to the first embodiment, since the power converter 2 resumes operation immediately after the voltage Vc of the regenerative energy storage means 3 drops below the power converter operable voltage value V3, the operation of the power converter 2 It is also conceivable that the power converter 2 stops for some reason soon after the restart and the short-circuit means 7 operates to energize the switching element. In this case, the temperature rises due to energization before the temperature of the switching element of the short-circuit means 7 is sufficiently lowered. If such a thing is assumed, in the overvoltage protection apparatus which concerns on Embodiment 1, it is necessary to use a large capacity | capacitance with a high heat-resistant temperature for the switching element of the short circuit means 7. FIG.
However, according to the overvoltage protection device for the synchronous machine according to the present embodiment, the stop set time ST is longer than the sum of the regenerative energy discharge period and the discharge period, and the temperature of the switching element of the short-circuit means 7 Therefore, even if the switching element of the short-circuit means 7 is continuously operated, the temperature of the switching element does not rise more than necessary, and a failure can be avoided. At the same time, since the heat resistant temperature is lower and the capacity can be selected, the cost can be reduced.

  According to the overvoltage protection device according to the present embodiment, the effect obtained by the overvoltage protection device according to the first embodiment can be obtained, and even if the switching element of the short-circuit means 7 is heated by energization due to a short circuit, the short-circuit state ends. If the stop set time ST is set so as to secure a sufficient time for the temperature drop due to the short circuit, even if the switching element of the short circuit 7 is frequently short-circuited / opened, the temperature of the switching element is excessive. Therefore, it is possible to avoid a failure. In addition, since the switching element of the short-circuit means 7 can be selected with a lower heat-resistant temperature and a smaller capacity, the cost of the overvoltage protection device can be reduced.

In the two embodiments described above, the discharge period is provided after the regenerative energy suppression period. However, it is not always necessary to start the discharge period after the end of the regenerative energy suppression period. For example, the discharge period may be started before the end of the regenerative energy suppression period, or the regenerative energy suppression period and the discharge period may be started simultaneously. Further, the discharge period may be started before the regenerative energy suppression period. Thus, it goes without saying that the same effect as the present invention can be obtained regardless of the relationship between the regenerative energy suppression period and the discharge period.
By providing a part of or all of the regenerative energy suppression period and the discharge period, the power converter 2 can be restored in a shorter time.

  The present invention is suitable for an overvoltage protection device that protects a capacitor and a power converter in a driving device that drives the synchronous machine from an overvoltage caused by a no-load induced voltage generated in the synchronous machine.

1 Synchronous machine, 2 Power converter, 3 Regenerative energy storage means, 4 DC power supply,
5, 13 Regenerative power suppressor, 6 Voltage detection means, 7 Short circuit means,
8, 12 Short-circuit control means, 8a, 8b, 8c comparison means,
8d, 8e AND means, 8f inversion means, 8g latch means,
9 discharge means, 9a discharge switching means, 9b discharge resistance, 9c release means,
10, 20 Overvoltage protection device, 11a timer, 11b Time comparison means.

Claims (4)

A DC power source that is a power source for driving the synchronous machine, a power converter that converts a DC current output from the DC power source into an AC current and outputs the AC current, and the DC power source and the power converter. An overvoltage protection device for a synchronous machine drive device having regenerative energy storage means connected in parallel to each other and storing regenerative energy generated in the synchronous machine,
A regenerative power suppressor connected to the synchronous machine and the power converter, detecting a no-load induced voltage due to regenerative energy generated in the synchronous machine, and suppressing the regenerative energy based on the no-load induced voltage; A discharge means connected in parallel to the regenerative energy storage means, and discharging the regenerative energy storage means in accordance with an instruction based on the no-load induced voltage from the regenerative power suppressor,
The regenerative power suppressor is
When the no-load induced voltage reaches a regenerative energy suppression start voltage value that is less than the breakdown voltage value of the regenerative energy storage means, an operation to suppress the regenerative energy is started, and the no-load induced voltage is suppressed to the regenerative energy suppression. When the regenerative energy suppression end voltage value smaller than the start voltage value is reached, the operation for suppressing the regenerative energy is terminated, and an instruction based on the no-load induced voltage is issued to the discharge means, and the regenerative power suppressor regenerative Operate the discharge means after starting the energy suppression operation, and suppress the regenerative energy by short-circuiting the lines of the synchronous machine,
The discharging means includes
Connected in parallel with the DC power supply,
While the no-load induced voltage transitions from the regenerative energy suppression start voltage value to the power converter operable voltage value at which the power converter can operate, and until the temperature at which the short-circuit means becomes operable, While cutting off the power supply from the DC power supply,
Discharging the regenerative energy storage means while the no-load induced voltage transitions from the regenerative energy suppression end voltage value to the power converter operable voltage value;
Overvoltage protection device characterized by. The regenerative power suppressor is
Voltage detecting means for detecting the value of the no-load induced voltage, comprising rectifying means connected in series to the three-phase lines of the synchronous machine, the output side being connected together;
One of both ends is connected to the output side of the rectifying means, the other is connected to the power converter, and short-circuit means for short-circuiting the lines of the synchronous machine by short-circuiting both ends;
Short-circuit control means connected in parallel with the short-circuit means, inputs the no-load induced voltage detected by the voltage detection means, and controls the operation of the short-circuit means based on the value of the no-load induced voltage;
With
The discharging means includes
Power supply from the DC power supply is performed until the no-load induced voltage changes from the regenerative energy suppression start voltage value to the power converter operable voltage value and reaches a temperature at which the short-circuiting unit can operate. An opening means to shut off;
A discharge resistor for consuming the regenerative energy stored in the regenerative energy storage means;
Based on the value of the no-load induced voltage, discharge switching means for opening and closing a circuit connecting the discharge resistor and the regenerative energy storage means,
The overvoltage protection device according to claim 1 , further comprising: The short-circuit control means includes
A first comparing means for inputting the no-load induced voltage value and comparing the no-load induced voltage value and the regenerative energy suppression start voltage value; the no-load induced voltage value and the regenerative energy suppression end voltage value; Second comparison means for comparing the voltage, third comparison means for comparing the no-load induced voltage value and the power converter operable voltage value, and latch means for holding the ON output of the first comparison means A timer that starts counting time from when the output of the first comparison means is turned on, a time comparison means that compares the output of the timer and a stop set time as a time to release the latch, First AND operation means for calculating the logical product of the output of the first comparison means and the output of the second comparison means; the output of the first comparison means and the output of the second comparison means; Inversion and the third comparison means Comprising a second logical product calculating means for calculating a logical product of the force, and
In order to control the operation of the opening means, the output of the first comparison means is output to the opening means, and in order to control the operation of the short-circuit means, the output of the first AND operation means is In order to output to the short-circuit means and control the operation of the discharge switching means, the output of the second AND operation means is output to the discharge switching means,
Releasing the latch means based on the output of the time comparison means;
The overvoltage protection device according to claim 2 . A DC power source that is a power source for driving the synchronous machine, a power converter that converts a DC current output from the DC power source into an AC current and outputs the AC current, and the DC power source and the power converter. An overvoltage protection device for a synchronous machine drive device having regenerative energy storage means connected in parallel to each other and storing regenerative energy generated in the synchronous machine,
A regenerative power suppressor connected to the synchronous machine and the power converter, detecting a no-load induced voltage due to regenerative energy generated in the synchronous machine, and suppressing the regenerative energy based on the no-load induced voltage; A discharge means connected in parallel to the regenerative energy storage means, and discharging the regenerative energy storage means in accordance with an instruction based on the no-load induced voltage from the regenerative power suppressor,
The regenerative power suppressor is
The rectifier includes a rectifier connected in series to the three-phase lines of the synchronous machine and connected together on the output side, and a voltage detector for detecting the value of the no-load induced voltage, and one of both ends is the output side of the rectifier The other is connected to the power converter, the short-circuit means for short-circuiting the lines of the synchronous machine by short-circuiting both ends, the no-load detected by the voltage detection means connected in parallel with the short-circuit means Short-circuit control means for inputting an induced voltage and controlling the operation of the short-circuit means based on the value of the no-load induced voltage, and the no-load induced voltage is less than the breakdown voltage value of the regenerative energy storage means When the regenerative energy suppression start voltage value is reached, an operation for suppressing the regenerative energy is started, and the no-load induced voltage is smaller than the regenerative energy suppression start voltage value. Ends the operation to suppress the regenerative energy when the voltage value is reached, issues an instruction to the discharge means based on the no-load induced voltage, and starts the regenerative energy suppression operation of the regenerative power suppressor after the start of the regenerative energy suppression operation. Operate
The discharging means includes
Based on the value of the no-load induced voltage, an opening means for cutting off power supply from the DC power supply, a discharge resistor for consuming the regenerative energy stored in the regenerative energy storage means, and the no-load induction A discharge switching means for opening and closing a circuit connecting the discharge resistor and the regenerative energy storage means based on a voltage value, connected in parallel with the DC power supply, and the no-load induced voltage is During the transition from the regenerative energy suppression start voltage value to the power converter operable voltage value at which the power converter is operable, the power supply from the DC power supply is cut off, and the no-load induced voltage is the regenerative energy. While transitioning from the suppression end voltage value to the power converter operable voltage value, discharging the regenerative energy storage means,
And the short-circuit control means includes
A first comparing means for inputting the no-load induced voltage value and comparing the no-load induced voltage value and the regenerative energy suppression start voltage value; the no-load induced voltage value and the regenerative energy suppression end voltage value; Second comparison means for comparing the voltage, third comparison means for comparing the no-load induced voltage value and the power converter operable voltage value, and latch means for holding the ON output of the first comparison means A first AND operation means for calculating a logical product of the output of the first comparison means and the output of the second comparison means, and the output of the first comparison means and the second comparison means A second AND operation means for calculating an AND of the output of the third comparison means and the output of the third comparison means, and for controlling the operation of the opening means, the first comparison means Output to the opening means and control the operation of the short-circuit means In order to output the output of the first AND operation means to the short-circuit means and to control the operation of the discharge switching means, the output of the second AND operation means is switched to the discharge switching. And releasing the latch means based on the output of the third comparing means.
Overvoltage protection device characterized by.

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