JP4121972B2 - Inverter device - Google Patents

Description

  The present invention relates to an inverter device that supplies electric power from a power supply to an inverter via a relay.

  In a conventional device that uses an electric motor, a relay controlled by a control device is connected in series to the power line of the electric motor so that the electric motor can be de-energized when an abnormality occurs in the device. ing. The contacts of this type of power relay are closed during normal device operation, and power is supplied to the electric motor via the contacts.

  By the way, there is a case where a large current flows through the electric motor due to a malfunction of the apparatus or other causes, but the large current also flows through the contact of the power relay. Two relays are arranged in parallel so that the contact resistance of the relay contacts is sufficiently small, and one relay is devised to prevent inrush current. The relay is welded due to large heat generation due to a temporary increase in contact resistance when the contact is opened or closed, which causes a large current to flow or is cut off, and discharge at the contact when the flowing current is cut off. Resulting in. If one of the two relays provided in parallel fails and the contacts are welded, the device may become uncontrollable and may not move. Accordingly, a power relay failure detection device that detects relay contact welding has been proposed (see Patent Document 1).

This power relay failure detection device is provided with contact abnormality detection means. Then, the voltage of the secondary power supply line is measured by the contact abnormality detecting means, and if the relay contact is not welded, the measured voltage is zero, and if the relay contact is welded, the measured voltage is higher than zero. The welding of the relay contact is detected based on the value of the measured voltage detected by the contact abnormality detecting means.
Japanese Patent No. 3097723

  However, in the past, when two relays provided in parallel were opened, the terminal voltages before and after the relay were compared, and if the measured voltage was zero, it was determined that the relay contact was welded. Therefore, the measured voltage does not become zero immediately due to the discharge voltage. For this reason, there has been a problem that the terminal voltages before and after the relay cannot be measured until the charging voltage of the capacitor disappears.

  In addition, when the device is provided with a booster circuit that boosts the power supply voltage, the voltage on the side opposite to the power supply of the booster circuit may become higher immediately after the relay is opened and before the capacitor is completely discharged. There was a problem that the measured voltage did not immediately become zero and the terminal voltage before and after the relay could not be measured. Therefore, it has been desired to develop a device that can detect the welding of the relay contact more accurately.

  The present invention has been made to solve the problems of the related art, and accurately detects relay welding in an inverter device having a booster circuit without newly adding a relay welding detection circuit. For the purpose.

That is, the inverter device of the present invention is an inverter device that supplies power to the inverter from a power source via a relay, a booster circuit provided between the relay and the inverter, a capacitor connected in parallel to the inverter, and the capacitor in parallel. It has a connected discharge resistor and a control device for controlling the booster circuit, relay and inverter, and this control device has a detecting means for detecting the terminal voltage of the capacitor and boosts the voltage in a state where the relay is disassembled. When the output of the circuit is boosted to the set maximum voltage, a welding detection process is performed to determine whether the capacitor terminal voltage is higher than before boosting.If the capacitor terminal voltage is higher than before boosting, It is characterized by judging.

  In the inverter device according to the second aspect of the present invention, in the above, the control device executes the welding detection process a predetermined number of times, and determines that the relay is welded when the terminal voltage of the capacitor is higher than that before boosting. And

According to the present invention, in an inverter device that supplies power to an inverter from a power source via a relay, a booster circuit provided between the relay and the inverter, a capacitor connected in parallel to the inverter, and the capacitor connected in parallel A resistance for discharging and a control device for controlling the booster circuit, the relay and the inverter are provided. The control device has detection means for detecting the terminal voltage of the capacitor, and the output of the booster circuit in a state where the relay is broken. When the capacitor is boosted to the set maximum voltage, welding detection processing is performed to determine whether the capacitor terminal voltage is higher than before boosting. If the capacitor terminal voltage is higher than before boosting, it is determined that the relay is welded. Therefore, it is possible to accurately detect the welding of the relay in the inverter device having the booster circuit without newly adding a relay welding circuit. Door will be able to.

  Further, as described in claim 2, if the welding detection process is executed a predetermined number of times, and it is determined that the relay is welded when the terminal voltage of the capacitor is higher than before boosting, the judgment of welding due to a temporary malfunction is eliminated. In addition, it is possible to determine the welding of the relay more reliably.

  In order to detect welding of a relay in an inverter device having a booster circuit, the present invention is provided with detection means and a control device for detecting a terminal voltage of a capacitor connected in parallel to the inverter. The purpose of detecting the welding of the relay was realized by a simple measurement just by measuring the terminal voltage of the capacitor.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an electric circuit diagram of an electric vehicle according to an embodiment provided with an inverter device 1 of the present invention, and FIG. 2 is a flowchart illustrating the operation of the inverter device 1 of the present invention.

  In FIG. 1, reference numeral 2 denotes a power source (in this case, a fuel cell) mounted on a fuel cell vehicle (FCEV). The positive terminal of the power source 2 supplies the voltage of the power source 2 via the main relay 3. It is connected to a booster circuit 4 that boosts the voltage to a predetermined set voltage, and this booster circuit 4 is connected to an inverter 5. The booster circuit 4 includes a reactor, a diode, a switching power transistor, and the like (not shown). The base of the transistor is controlled so as to boost the power supply voltage so that a motor M described later can be driven. It is configured.

  Further, the negative terminal of the power source 2 is connected to an inverter 5 through a booster circuit 4, and the inverter 5 is connected to a motor M for running a fuel cell vehicle. In this case, the inverter 5 converts the electric power boosted by the booster circuit 4 into a frequency and voltage at which the motor M can be driven to drive the automobile. Although not shown, a plurality of switching elements and switching surge absorbing diodes are not shown. The DC power from the power source 2 is converted into a motor drive waveform and applied to the motor M. As a result, the motor M is driven to drive the automobile.

  Between the positive terminal of the power source 2 and the main relay 3, one terminal of an inrush current prevention relay 6 in which a switch SW1 is connected in series is connected via a resistor R1. The other terminal of the inrush current prevention relay 6 is connected between the main relay 3 and the booster circuit 4, and the main relay 3 and the inrush current prevention relay 6 are connected in parallel.

  The inrush current prevention relay 6 is connected to a control device 8 (shown as a control circuit in FIG. 1) constituted by a general-purpose microcomputer. This inrush current prevention relay 6 is closed before the main relay 3 by the control device 8 and absorbs an excessive inrush current from the power source 2 by the resistor R1 constituting the inrush current prevention relay 6, while the power is boosted. The capacitor C <b> 1 described later is charged via 4.

  Further, an input voltage detection circuit 9 is connected across the positive side terminal and the negative side terminal of the power supply 2, and this input voltage detection circuit 9 is connected to the control device 8. The input voltage detection circuit 9 is composed of, for example, two resistors (not shown) connected in series, and the control device 8 detects the voltage of the power supply 2 by detecting the voltage between the two resistors. And the voltage of the power source 2 is monitored.

  A resistor R2 is connected between one terminal of the booster circuit 4 between the booster circuit 4 and the inverter 5 and the other terminal of the booster circuit 4, and a capacitor C1 is connected in parallel to the resistor R2. It is connected. The capacitor C1 has one terminal side of the booster circuit 4 connected to + and the other terminal side connected to-. The capacitor C1 plays a role of correcting the voltage drop when the inverter 5 is ON and absorbing the back electromotive force from the motor M when the inverter 5 is OFF and discharging the charging voltage charged in the capacitor C1.

  Further, the charging voltage detection circuit 19 (terminal of the capacitor of the present invention) is connected in parallel with the capacitor C1 across one terminal of the boosting circuit 4 between the boosting circuit 4 and the inverter 5 and the other terminal of the boosting circuit 4. Connected to a detecting means for detecting a voltage). The charging voltage detection circuit 19 detects the terminal voltage across the capacitor C1, and monitors the charging voltage of the capacitor C1. And the control apparatus 8 detects the charging voltage of the capacitor | condenser C1 with the charging voltage detection circuit 19, and when the charging voltage of the capacitor | condenser C1 rises to a predetermined value, the main relay 3 will be torn. Thereby, the control device 8 blocks the flow into the inverter 5 and the booster circuit 4 due to the counter electromotive force of the motor M, and protects them from being damaged by the counter electromotive force.

  When the electric circuit of the electric vehicle is turned on, the control device 8 first closes the inrush current prevention relay 6 and controls the capacitor C1 through the booster circuit 4 while controlling an excessive inrush current from the power source 2 with the resistor R1. To charge. When the charging voltage detection circuit 19 detects that the charging voltage of the capacitor C1 has increased to a predetermined value after a predetermined time has elapsed, the control device 8 closes the main relay 3 and then breaks the inrush current prevention relay 6 to supply power. 2 is directly boosted by the booster circuit 4 and applied to the inverter 5. The inverter 5 converts the applied DC power into a motor drive waveform and applies it to the motor M, whereby the motor M is driven to run the automobile.

  On the other hand, if any of the main relay 3 or the inrush current prevention relay 6 breaks down and the contact is welded, the control of the apparatus becomes impossible, but the control device 8 does not control the main relay 3 or the inrush current prevention relay 6. There are two types of detection functions when welding.

  First, the first welding detection function will be described with reference to the flowchart of FIG. The control device 8 includes a storage device (not shown). Further, the control device 8 normally controls the booster circuit 4 without boosting the maximum voltage, but the booster circuit 4 can be set up to the maximum voltage on the electric circuit with the main relay 3 and the inrush current prevention relay 6 broken. It is assumed that a notification means such as a sound or a lamp is provided.

  In step S1, the control device 8 starts the welding detection process after the main relay 3 and the inrush current prevention relay 6 are broken, or starts the welding detection process before closing the contacts of the main relay 3 and the inrush current prevention relay 6. To do. Next, the control device 8 detects the voltage across the capacitor C1 from the charging voltage detection circuit 19 in step S2, and stores the charging voltage (1) in the storage device. In this case, the control device 8 executes the welding detection process a predetermined number of times to prevent a temporary malfunction.

  Accordingly, it is determined that the relay is welded when the terminal voltage of the capacitor C1 is higher than that before boosting. In step S3, the control device 8 performs control to boost the booster circuit 4 to the maximum voltage after a predetermined time has elapsed, and then proceeds to step S4. Therefore, the control device 8 detects again the voltage across the capacitor C1 from the charging voltage detection circuit 19, and the charging voltage (2) across the capacitor C1 measured at present from the previous charging voltage (1) stored in the storage device. Determine which is bigger. The charging voltages (1) and (2) are indicated by circles 1 and 2 in the figure.

  In this case, since the resistor R2 or the inverter 5 is connected to both ends of the capacitor C1, the boosting circuit 4 is boosted up to the set maximum voltage after a predetermined time has elapsed after measuring the charging voltage (1) across the capacitor C1. Otherwise, the charging voltage of the capacitor C1 is discharged by the resistor R2 or the inverter 5, and the charging voltage (1) is lowered, but the contact of either the main relay 3 or the inrush current prevention relay 6 is welded. If so, the power source 2 passes through the main relay 3 or the inrush current prevention relay 6 and is boosted by the booster circuit 4 to charge the capacitor C1. Due to this charging, the charging voltage (2) at both ends of the capacitor C1 measured at present is higher than the previous charging voltage (1) stored in the storage device. Similarly, before closing the contacts of the main relay 3 and the inrush current prevention relay 6, the charging voltage (2) at both ends of the capacitor C1 measured at present is higher than the previous charging voltage (1).

  That is, in step S4, the control device 8 proceeds to step S5 when the charging voltage (2) at both ends of the capacitor C1 currently measured is larger than the previous charging voltage (1) stored in the storage device. 3 or the contact point of the inrush current prevention relay 6 is determined to be welded. In step S6, the control device 8 informs that the contact of either the main relay 3 or the inrush current prevention relay 6 is welded by a not-shown notifying means, and ends the welding detection process.

  In step S4, if the charging voltage (2) at both ends of the capacitor C1 currently measured is smaller than the previous charging voltage (1) stored in the storage device, the control device 8 proceeds to step S7, where the main relay 3 Alternatively, both of the inrush current prevention relays 6 are determined to be normal without the contacts being welded. In step S8, the control device 8 notifies that the main relay 3 or the inrush current prevention relay 6 is normal by notifying means (not shown) and ends the welding detection process.

  As described above, the control device 8 includes the charging voltage detection circuit 19 that detects the terminal voltage of the capacitor C1, and sets the output of the booster circuit 4 in a state where the main relay 3 and the inrush current prevention relay 6 are broken. Boost to. At this time, welding detection processing is performed to determine whether or not the terminal voltage of the capacitor C1 is higher than before boosting. When the terminal voltage of the capacitor C1 is higher than before boosting, both the main relay 3 and the inrush current prevention relay 6 are Alternatively, since either one of the contacts is determined to be welded, the inverter device having the booster circuit 4 can be obtained without newly adding a contact welding circuit for the relays 3 and 6. It is possible to detect contact welding of one relay 3 and 6.

  Further, since the control device 8 executes the welding detection process a predetermined number of times, the welding determination of the contacts of the main relay 3 and the inrush current prevention relay 6 due to a temporary malfunction is eliminated, and the relay welding determination is performed more reliably. be able to.

  Next, the second welding detection function will be described with reference to the flowchart of FIG. The control device 8 is assumed to have the same function as described above. In step S11, the control device 8 starts the welding detection process when the inverter 5 is in normal use (in this case, when the booster circuit 4 is not used at the maximum voltage). Next, in step S12, the control device 8 waits for the main relay 3 and the inrush current prevention relay 6 to be in a ruptured state. When the main relay 3 and the inrush current prevention relay 6 are in a ruptured state, the process proceeds to step S13.

  Therefore, the control device 8 detects the charging voltage at both ends of the capacitor C1 by the charging voltage detection circuit 19, and stores the charging voltage (1) at both ends of the capacitor C1 currently measured in the storage device. In step S14, the control device 8 boosts the booster circuit 4 to the set maximum voltage after a lapse of a predetermined time, and proceeds to step S15. The charge voltage detection circuit 19 detects the charge voltage across the capacitor C1 again and stores it last time. It is determined whether the charging voltage (2) at both ends of the capacitor C1 currently measured is greater than the previous charging voltage (1).

  Also in this case, since the resistor R2 or the inverter 5 is connected to both ends of the capacitor C1 as described above, the booster circuit 4 is set to the set maximum voltage after a predetermined time has elapsed after measuring the charging voltage (1) at both ends of the capacitor C1. If the voltage is not boosted to the maximum, the charging voltage of the capacitor C1 is discharged by the resistor R2 or the inverter 5, and the charging voltage (1) is lowered, but the contact of either the main relay 3 or the inrush current prevention relay 6 is connected. In the case of welding, the power source 2 passes through the main relay 3 or the inrush current prevention relay 6 and is boosted by the booster circuit 4 to be charged in the capacitor C1. The charging voltage (2) at both ends of the capacitor C1 measured at present is higher than the previous charging voltage (1) stored by this charging. Similarly, before closing the contacts of the main relay 3 and the inrush current prevention relay 6, the charging voltage (2) at both ends of the capacitor C1 measured at present is higher than the previous charging voltage (1).

  That is, in step S15, the control device 8 proceeds to step S16 when the charging voltage (2) at both ends of the capacitor C1 measured at present is larger than the previously stored charging voltage (1), and then proceeds to step S16. It is determined that one of the contacts of the current prevention relay 6 is welded. In step S <b> 17, the control device 8 informs that the contact of either the main relay 3 or the inrush current prevention relay 6 is welded by notifying means (not shown) and ends the welding detection process.

  In step S15, the control device 8 proceeds to step S18 when the charging voltage (2) across the capacitor C1 currently measured is smaller than the previously stored charging voltage (1), and proceeds to step S18, where the main relay 3 or inrush current is obtained. Both of the prevention relays 6 determine that the contacts are normal without welding. In step S19, the control device 8 notifies that the main relay 3 or the inrush current prevention relay 6 is normal by notifying means (not shown) and ends the welding detection process.

  Thus, even when the inverter 5 is in normal use, the control device 8 can perform the welding detection process when the booster circuit 4 is not used at the maximum voltage. Thereby, the contact welding of the relays 3 and 6 of the inverter device 1 having the booster circuit 4 can be detected without newly adding a contact welding circuit for the main relay 3 and the inrush current prevention relay 6 as described above. It is convenient. Also, if the welding detection process is executed a predetermined number of times by the control device 8 as described above, and it is determined that the relay is welded when the terminal voltage of the capacitor C1 is higher than before boosting, the welding judgment due to a temporary malfunction will occur. This makes it possible to more reliably determine the relay welding.

  Next, FIG. 4 shows an electric circuit diagram in the case where surplus power of a household fuel cell according to an embodiment including the inverter device 1 according to another embodiment of the present invention is sold to a commercial power company. . Hereinafter, different parts will be described. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 4, a commercial AC power supply AC is connected to the subsequent stage of the inverter 5 instead of the motor M described above. A link protection device 20 is provided between the commercial AC power supply AC and the inverter 5 to provide a relay and to protect the amount of power sold and the backflow protection from the commercial AC power supply AC to the inverter 5. In this case, the inverter 5 converts the DC power into a frequency and voltage that can be used in a general household. In addition, about the technique which converts direct-current power into the frequency and voltage which can be used in a general household, since it is a conventionally well-known technique, detailed description is abbreviate | omitted. In addition, a household fuel cell is used.

  As described above, even when the AC commercial power supply AC is connected to the inverter 5 instead of the motor M of the electric vehicle according to the first embodiment, surplus power generated by the home fuel cell is sold, the terminal of the capacitor C1 is used. When the voltage is higher than before boosting, it can be determined that both the main relay 3 and the inrush current prevention relay 6 or one of the contacts is welded, so that the same effect as described above can be obtained. it can. Thereby, the versatility of the inverter apparatus 1 can be expanded and the convenience of the inverter apparatus 1 can be improved significantly.

  Next, FIG. 5 shows an electric circuit diagram in the case where the home air conditioner AC of one embodiment provided with the inverter device 1 of another embodiment of the present invention is controlled by the inverter 5. Hereinafter, different parts will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 5, when the home air conditioner AC is controlled by the inverter 5, the power source 2 composed of a commercial AC power source of 100 V or 200 V is connected in place of the fuel cell of the first embodiment, and the input voltage detection circuit 9 A rectifier circuit 30 (diode bridge) for converting the power source 2 (commercial AC power source) into a direct current is connected between the main relay 3 and the main relay 3. Further, a household air conditioner AC (M in the figure) is connected to the subsequent stage of the inverter 5 in place of the motor M described above, and the inverter 5 converts DC power into a frequency and voltage that can drive the household air conditioner AC. As the input voltage detection circuit 9, a circuit that can detect the voltage of the power source 2 (commercial AC power source) is used.

  As described above, the inverter 5 is connected to the commercial AC power source (power source 2) instead of the fuel cell (power source 2) of the first embodiment, and also connected to the home air conditioner AC instead of the motor M of the electric vehicle. When the terminal voltage of the capacitor C1 is higher than before boosting, it can be determined that both the main relay 3 and the inrush current prevention relay 6 or one of the contacts is welded. An effect can be obtained. Thereby, the versatility of the inverter apparatus 1 can be expanded and the convenience of the inverter apparatus 1 can further be improved.

  Next, FIG. 6 shows an electric circuit diagram in the case where the home air conditioner AC of one embodiment provided with the inverter device 1 of another embodiment of the present invention is controlled by the inverter 5. Hereinafter, different parts will be described. The same parts as those in the third embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In this case, as shown in FIG. 6, the rectifier circuit 30 provided for converting the power source 2 (commercial AC power source) to DC is removed between the input voltage detection circuit 9 and the main relay 3 in the third embodiment, A rectifier circuit 30 is connected between the main relay 3 and the booster circuit 4. The main relay 3 and the inrush current prevention relay 6 are operated by a power source 2 (commercial AC power source).

  As described above, the rectifier circuit 30 is provided between the main relay 3 and the booster circuit 4, and a commercial AC power supply (power supply 2) is connected to the inverter 5 instead of the fuel cell (power supply 2) of the first embodiment. Even when a home air conditioner AC is connected in place of the motor M of the automobile, if the terminal voltage of the capacitor C1 is higher than before boosting, both the main relay 3 and the inrush current prevention relay 6 or either one of them. Since it can be determined that the contact is welded, the same effect as described above can be obtained. Thereby, the versatility of the inverter apparatus 1 can be expanded and the convenience of the inverter apparatus 1 can be improved further significantly.

It is an electric circuit diagram of the electric vehicle of one Example provided with the inverter apparatus of this invention. Example 1 It is a flowchart which shows the control action of one Example of the inverter apparatus of this invention. It is a flowchart which shows other control operation of one Example of the inverter apparatus of this invention. It is an electric circuit diagram in the case of selling the surplus electric power of the household fuel cell of one Example provided with the inverter apparatus of the other Example of this invention to a commercial power company. (Example 2) It is an electric circuit diagram in the case of controlling the household air conditioner etc. of one Example provided with the inverter apparatus of the other Example of this invention by an inverter. (Example 3) It is an electric circuit diagram in the case of controlling another household air conditioner of one Example provided with the inverter apparatus of the other Example of this invention with an inverter. Example 4

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inverter apparatus 2 Power supply 3 Main relay 4 Booster circuit 5 Inverter 6 Inrush current prevention relay 8 Controller 9 Input voltage detection circuit 19 Charge voltage detection circuit C1 Capacitor M Motor

Claims (2)

In the inverter device that supplies power from the power source to the inverter via the relay,
A booster circuit provided between the relay and the inverter;
A capacitor connected in parallel to the inverter;
A discharging resistor connected in parallel to the capacitor;
A control device for controlling the booster circuit, the relay and the inverter;
The control device includes detection means for detecting a terminal voltage of the capacitor, and when the output of the booster circuit is boosted to a set maximum voltage in a state where the relay is disengaged, the terminal voltage of the capacitor is not boosted. An inverter device characterized by performing a welding detection process for determining whether or not the relay is higher, and determining that the relay is welded when the terminal voltage of the capacitor is higher than that before boosting.   2. The inverter device according to claim 1, wherein the control device executes the welding detection process a predetermined number of times, and determines that the relay is welded when the terminal voltage of the capacitor is higher than that before boosting.

Images