JP2009124915A - Inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inverter device which prevents unstable inverter operation due to variations in the power supply voltage, immediately after the power is turned on, even when a power smoothing capacitor with a small capacity is used, and which has the size and the cost and the reliability improved. <P>SOLUTION: The duty ratio of at least one switching element is controlled, before outputting a pseudo-AC waveform immediately, after a DC power supply 1 is turned on; and suppressed charging is conducted with the other switching elements in the off state, thereby the variations in the power supply voltage can be suppressed ;and a capacitor of a charge pump circuit can be charged within a practical time frame, without having to increase the capacity of the power smoothing capacitor 9 for a drive circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inverter device using a charge pump system in a drive circuit of a switching element that generates a pseudo AC waveform output.

  For this type of inverter device, there has been proposed a method of suppressing charging by arbitrarily changing the duty and cycle of the negative side switching element in the ON and OFF states (see, for example, Patent Document 1).

  FIG. 6 shows an inverter device using the conventional charge pump system described in I.

  In FIG. 6, 1 is a DC voltage source, 2a to 2f are switching elements, 3a to 3c are drive circuits for driving switching elements (hereinafter referred to as upper arms) connected to the positive side of the DC voltage source 1, and diodes A predetermined voltage is charged to the capacitor 5a serving as the power source of the drive circuit 3a via 4a. The capacitors 5b and 5c are similarly charged via the diodes 4b and 4c. At this time, the charging current to the capacitor 5a is suppressed with a predetermined duty. Reference numeral 3d denotes a drive circuit for driving a switching element 2d connected to the negative side of the DC voltage source 1 (hereinafter referred to as a lower arm). Reference numeral 7 denotes a minus side power supply line of the drive circuit 3a, 8 denotes a drive circuit power supply, and 9 denotes a drive circuit power supply smoothing capacitor.

  In the inverter device configured as described above, the switching elements 2a and 2d are connected to the DC voltage source 1 in a bridge shape, and the DC voltage output from the DC voltage source 1 is appropriately switched to thereby change the predetermined pseudo AC. Output the waveform.

  The drive circuit 3a for driving the switching element 2a of the upper arm constitutes a charge pump circuit together with the diode 4a and the capacitor 5a. That is, a predetermined voltage is supplied from the drive circuit power supply 8 through the diode 4a to the capacitor 5a, and the capacitor 5a is charged. The drive circuit 3a is driven by using the capacitor 5a as a power source.

  The drive circuit 3d that drives the switching element 2d of the lower arm is not provided with a diode and a capacitor because direct current power is supplied from the drive circuit power supply 8.

  Next, the operation of this inverter device will be described.

  When the switching element 2d of the lower arm is first turned on by a predetermined signal from the control circuit, the minus side power supply line 7 of the upper arm drive circuit 3a reaches almost the same potential as the minus side potential of the DC voltage source 1. Descent. At this time, the capacitor 5a of the drive circuit 3a for the upper arm is charged from the drive circuit power supply 8 through the diode 4a to almost the same potential as the drive circuit power supply 8.

Next, when the switching element 2d of the lower arm is turned off and the switching element 2a of the upper arm is turned on, the potential of the negative side power supply line 7 of the driving circuit 3a of the upper arm is changed to that of the DC voltage source 1 this time. It rises to almost the same potential as the plus side potential. In this state, the diode 4a is in a backflow blocking state, the electric charge of the capacitor 5a is maintained, and power is continuously supplied from the capacitor 5a to the drive circuit 3a. Thus, during normal waveform output, the capacitor 5a is automatically charged by PWM switching of the upper arm and the lower arm.
JP 2001-178147 A

  However, immediately after the power is turned on, the capacitors 5a, 5b, and 5c are not sufficiently charged, and the switching elements 2d, 2e, and 2f of the lower arms are suppressed and charged with a predetermined duty ratio. When the capacitance of the capacitor 9 is small, the power supply voltage may decrease.

  In the above conventional inverter device, in order to charge the capacitor of the charge pump circuit which is the power source of the upper arm drive circuit, all the lower arms are turned on at a predetermined duty ratio and charging to the capacitors 5a, 5b and 5c is started. Then, when the capacity of the drive power supply capacitor 9 is small, the drive circuit power supply voltage fluctuates, and in the worst case, there is a problem that the function of the inverter is stopped because it becomes lower than the gate drive voltage level of the switching element. For this reason, the drive circuit power supply smoothing capacitor 9 requires a relatively large capacity in order to suppress voltage fluctuation.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide an inverter device that is improved in size, cost, and reliability without increasing the capacity of a power supply smoothing capacitor for a drive circuit.

  In order to solve the above-described conventional problems, an inverter device according to the present invention includes a plurality of pairs in a pair configuration of a positive side switching element and a negative side switching element respectively connected between a positive side and a negative side of a DC voltage. Switching means, a drive circuit for driving the switching element, a capacitor of a charge pump circuit that is a power source of the drive circuit for the switching element connected to the positive side of the DC voltage, and a drive circuit for charging the capacitor The power supply smoothing capacitor for the power supply and the drive circuit, and before the AC waveform output, the duty cycle is controlled for any one of the negative switching elements in the switching period of the switching means, and the others. The switching element in the OFF state is charged with suppression It is provided with a control means.

  This control means can suppress fluctuations in the power supply of the power supply smoothing capacitor for the drive circuit.

  The inverter device of the present invention controls the duty ratio for at least one switching element before outputting the pseudo AC waveform immediately after the DC power is turned on, and the other switching elements are in the OFF state to suppress and charge the drive circuit. Without increasing the capacity of the power supply smoothing capacitor, it is possible to suppress fluctuations in the power supply of the power supply smoothing capacitor for the drive circuit and to charge the capacitor of the charge pump circuit in a time within the practical range.

  The first invention is provided with a control means for controlling the duty ratio for any one of a plurality of switching elements on the negative side, and the other switching elements being controlled to be charged while being in an OFF state. Since the charging current flows only from the circuit power supply smoothing capacitor to the capacitor of the upper arm whose duty ratio is controlled, fluctuations in the power supply of the drive circuit power supply smoothing capacitor can be suppressed.

  The second aspect of the invention further includes a control means for controlling the duty ratio from the power supply smoothing capacitor for the drive circuit by providing a control means for sequentially switching and controlling the switching elements for controlling the duty ratio for each switching cycle, thereby controlling the duty ratio from the power supply smoothing capacitor for the drive circuit. Only the charging current flows and charging can flow to the capacitors of the plurality of charge pump circuits, so that the power supply fluctuation of the power supply smoothing capacitor for the drive circuit can be suppressed.

  The third aspect of the invention further includes control means for suppressing charging by gradually increasing the duty ratio to be operated, so that the power supply fluctuation of the power supply smoothing capacitor for the drive circuit can be more effectively suppressed.

  The fourth invention is an inverter device mounted on an inverter for a compressor integrated type. Under conditions where the inverter occupying volume is severe, the capacity of the power supply smoothing capacitor for the drive circuit can be kept small, and the inverter part can be downsized. Is effective.

  The fifth invention is an inverter device mounted on a vehicle, the space that can be mounted in the vehicle is limited, the capacity of the power supply smoothing capacitor for the drive circuit can be kept small, and the size of the inverter part is reduced. There is.

(Embodiment 1)
1 and 2 show a block diagram and a control timing chart of the charge pump control circuit of the inverter according to the first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a vehicle DC voltage source, 2a to 2f are insulated gate input switching elements, and IGBTs 3a to 3c are drive circuits for driving the upper arm switching elements. The drive circuit 3a is connected via a diode 4a. A predetermined voltage is charged in the capacitor 5a serving as a power source. The capacitors 5b and 5c are similarly charged through the diodes 4b and 4c, and each constitutes a charge pump circuit. Reference numeral 7 denotes a minus side power supply line of the drive circuit 3a. 3d to 3f are drive circuits for driving the switching elements 2d to 2f of the lower arm, 8 is a power supply for the drive circuit, 10 is a microcomputer of the PWM signal generating means of the control means, and the switching elements 2a through the drive circuits 3a to 3f Generates a signal to turn on and off 2f. What differs from the conventional example in the configuration is the control content of the control means 10.

  In the inverter device of this embodiment, the switching elements 2a to 2f are normally connected to the DC voltage source 1 in a bridge shape, and the DC voltage output from the DC voltage source 1 is appropriately switched to appropriately change the predetermined pseudo AC waveform. However, immediately after the DC power supply is turned on as in the conventional example, the capacitor 5a is not sufficiently charged, and the lower arm is always turned on for a sufficient time to charge the capacitor 5a before waveform output. There is a need.

  At this time, as shown in FIG. 2, the capacitor 5a is sufficiently charged until the first waveform is output, and the lower arm so that the voltage fluctuation of the drive circuit power supply 8 has a sufficient margin with respect to the gate drive voltage level. The duty of ON state of 2d and OFF state is controlled. At this time, charging of the capacitors 5b and 5c is stopped, so that the lower arms 2e and 2f are turned off.

  Next, after the charging of the capacitor 5a is completed, the capacitor 5b is fully charged, and the lower arm 2e is turned on and off so that the voltage fluctuation of the driving circuit power supply 8 has a sufficient margin with respect to the gate driving voltage level. The duty of the state is controlled. At this time, charging of the capacitors 5a and 5c is stopped, so that the lower arms 2d and 2f are turned off.

  Next, after the charging of the capacitor 5b is completed, the capacitor 5c is fully charged, and the lower arm 2f is turned on and off so that the voltage fluctuation of the drive circuit power supply 8 has a sufficient margin with respect to the gate drive voltage level. The duty of the state is controlled. At this time, charging of the capacitors 5a and 5b is stopped, so that the lower arms 2d and 2e are turned off.

  As described above, since the capacitors 5a, 5b, and 5c are not charged simultaneously from the drive circuit power supply 8 and the drive circuit power supply smoothing capacitor 9, the burden on the drive circuit power supply smoothing capacitor is reduced and the power supply voltage is lowered. Can be suppressed.

(Embodiment 2)
FIG. 3 shows a control timing chart of the charge pump control circuit of the inverter according to the second embodiment of the present invention. In this embodiment, the switching elements for duty control are sequentially switched for each switching period.

  Thereby, the capacitors 5a, 5b, and 5c are not charged simultaneously from the drive circuit power supply 8 and the drive circuit power supply smoothing capacitor 9, thereby reducing the burden on the drive circuit power supply smoothing capacitor and suppressing the drop in the power supply voltage. I can do it.

(Embodiment 3)
FIG. 4 shows a control timing chart of the charge pump control circuit of the inverter according to the third embodiment of the present invention. In the present embodiment, the switching elements for duty control are sequentially switched for each switching period, and the duty is gradually increased as shown in FIG. As a result, the burden on the power supply smoothing capacitor for the drive circuit can be further reduced, and the decrease in the power supply voltage can be suppressed.

(Embodiment 4)
The present invention is applied to an inverter device mounted on a compressor-integrated inverter, and the capacitor capacity can be reduced as much as the burden on the power supply smoothing capacitor for the drive circuit is reduced. As a result, the capacitor is reduced in size. Thus, the downsizing of the inverter device can be improved.

(Embodiment 5)
The present invention is applied to an inverter device mounted on a vehicle, and the capacitor capacity can be reduced as much as the burden on the power supply smoothing capacitor for the drive circuit is reduced. As a result, the capacitor can be reduced in size. By improving the downsizing of the inverter device, it is possible to improve the mountability to the vehicle.

  The inverter device of the present invention can reduce the load on the power supply smoothing capacitor for the drive circuit and can reduce the capacitor capacity. As a result, the capacitor can be reduced in size, and the inverter device can be reduced in size. Therefore, it can be applied to all inverters for driving a motor.

1 is a block diagram of a charge pump control circuit of an inverter according to Embodiment 1 of the present invention. Control timing chart of charge pump control circuit of inverter in embodiment 1 of the present invention Control timing chart of charge pump control circuit of inverter in embodiment 2 of the present invention Control timing chart of charge pump control circuit of inverter in embodiment 3 of the present invention Block diagram of a conventional inverter charge pump control circuit Control timing chart of conventional inverter charge pump control circuit

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC voltage source 2a-2f Switching element 3a-3f Drive circuit 5a-5c Capacitor 8 Power supply for drive circuits 9 Power supply smoothing capacitor for drive circuits 10 Control means (PWM signal generator)

Claims (5)

A plurality of pairs of switching means constituted by a plus side switching element and a minus side switching element respectively connected between the plus side and the minus side of the DC voltage; a drive circuit for driving the switching element; and a DC voltage A capacitor of a charge pump circuit that is a power supply of a drive circuit of a switching element connected to the plus side of the drive circuit, a power supply for the drive circuit for charging the capacitor and a power supply smoothing capacitor for the drive circuit, and before the AC waveform output, Inverter comprising control means for controlling duty ratio with respect to any one of a plurality of switching elements on the negative side in the switching cycle of the switching means and suppressing charging with the other switching elements being in an OFF state apparatus. 2. The inverter apparatus according to claim 1, wherein the control means sequentially switches and switches the switching elements that control the duty ratio for each switching period. The inverter apparatus according to claim 1, wherein the duty ratio to be operated is gradually increased. The inverter apparatus as described in any one of Claim 1 to 3 mounted in the inverter for compressor integrated type. The inverter apparatus as described in any one of Claims 1-4 mounted in a vehicle.