JP2012080740A - Inverter controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter controller that carries out accurate current detection even in the presence of noise interference in a power factor improvement circuit and an inverter circuit.SOLUTION: An inverter controller includes signal correction means 18 that corrects both or either one of respective switching signals and current detection timing of a power factor improvement circuit and an inverter circuit. The signal correction means 18 carries out accurate current detection by correcting both or either one of the respective switching signals and the current detection timing so that noise caused by the respective switching of the power factor improvement circuit and the inverter circuit does not interfere with respective current detection operations.

Description

  The present invention relates to an inverter control device including a power factor correction circuit.

  Conventionally, as this type of technology, for example, there is a device having a power factor correction circuit including a boost chopper circuit including a coil, an IGBT, a diode, and a current detection resistor after a rectifier (see, for example, Patent Document 1). .

JP-A-10-052050

  However, the conventional inverter control device has a problem that noise is superimposed on the current detection resistor due to switching of the IGBT and the inverter circuit.

  The present invention solves the above-described conventional problems, and corrects both or one of the switching signal and current detection timing of the power factor correction circuit and the inverter circuit, whereby the power factor correction circuit and the inverter circuit switch each other. An object of the present invention is to provide an inverter device that performs current detection without receiving noise interference.

  In order to solve the above-mentioned conventional problems, the inverter control device of the present invention is provided with signal correction means for correcting both or one of the switching signal and each current detection timing of the power factor correction circuit and the inverter circuit. Each switching signal and / or current detection timing is corrected so that current detection is not affected by noise interference caused by switching.

  The inverter control device according to the present invention corrects each switching signal and / or current detection timing so that each current detection of the power factor correction circuit and the inverter circuit is not affected by noise caused by each switching. Thus, it is possible to provide an inverter control device that can perform accurate current detection without being affected by noise interference.

Configuration diagram for explaining Embodiment 1 of the present invention Waveform graph explaining conventional current detection method Waveform graph explaining the problem to be solved Waveform graph for explaining switching signal correction of the power factor correction circuit by the signal correction means in the present invention Waveform graph for explaining switching signal correction of inverter circuit by signal correction means in the present invention Waveform graph for explaining the first correction method of the current detection timing by the signal correction means in the present invention Waveform graph for explaining the second correction method of the current detection timing by the signal correction means in the present invention

  A first aspect of the present invention is an inverter control device for driving a motor by rectifying and adjusting a voltage of an AC power source with a power factor correction circuit and then converting the AC power into arbitrary AC power with an inverter circuit. And PFC control means for creating current detection timing, inverter control means for creating switching signal and current detection timing of the inverter circuit, and signal correction means for correcting either or both of each switching signal and current detection timing And the signal correction means corrects both and / or one of each switching signal and current detection timing so that noise caused by each switching of the power factor correction circuit and the inverter circuit does not interfere with each current detection. Device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
FIG. 1 shows the configuration of an inverter control apparatus according to the first embodiment of the present invention.

  In FIG. 1, an AC power source 1 is connected to a power factor correction circuit 2, and AC power is converted into DC power. In the power factor correction circuit 2, the coil 4, the IGBT 5 and the shunt resistor 6 are connected in series to the output of the diode bridge 3, and the electrical energy stored in the coil 4 is smoothed via the diode 7 when the IGBT 5 is turned on. Store in capacitor 8. The output voltages of the diode bridge 3 and the smoothing capacitor 8 are sent to the PFC control means 11 via the input voltage detection circuit 9 and the DC voltage detection circuit 10, respectively, and via the input current detection circuit 12 connected to the shunt resistor 6. From the input current obtained in this way, the PFC control means 11 creates the switching signal of the IGBT 5 and the detection timing of the input current.

  On the other hand, an inverter circuit 14 that converts DC power to AC power and sends it to the motor 13 is connected to the smoothing capacitor 8 in series with the shunt resistor 15, and is obtained via the motor current detection circuit 16 connected to the shunt resistor 15. From the input current and the output voltage of the smoothing capacitor 8, the inverter control means 17 creates the switching signal of the inverter circuit 14 and the detection timing of the motor current. The switching signal and current detection timing output from the PFC control unit 11 and the inverter control unit 17 are corrected by the signal correction unit 18 for both or one of the switching signals and each current detection timing.

  FIG. 2 is a diagram for explaining a motor current detection method by a single shunt method, and FIG. 3 is a diagram for explaining the influence of switching of the IGBT 5 of the power factor correction circuit 2 on the one shunt method current detection. The motor current detection method by the one shunt method has already been put into practical use in many products, so that the details are omitted as it is known. Here, an example of the switching pattern and current acquisition timing of the U, V, W phases of the motor 13 is described. Show only.

  In FIG. 2, when switching of each phase of the inverter circuit 14 is performed assuming that the IGBT 5 of the power factor correction circuit 2 is not switched, the voltage across the shunt resistor 15 is caused by the wiring impedance of the circuit due to the current change at each switching. The ringing noise shown in the figure actually occurs. For this reason, a method is adopted in which a waveform stabilization wait time is provided rather than switching of each phase, and current acquisition is performed after ringing noise converges.

  Next, when the IGBT 5 of the power factor correction circuit 2 is switched as shown in FIG. 3, noise is generated due to the same factor and affects the inverter circuit 14, and the noise is detected at the current detection timing as shown in FIG. In some cases, the detection error may occur due to superimposition.

  The operation of the signal correction means in the present invention for solving these problems will be described with reference to FIGS.

  FIG. 4 is an example of avoiding interference noise by correcting the switching of the power factor correction circuit 2. By delaying the switching of the power factor correction circuit 2, it is possible to avoid the influence of interference noise without changing the timing of Iu detection.

  FIG. 5 is an example of avoiding interference noise by correcting the switching of the inverter circuit 14. The influence of interference noise can be avoided by advancing the timing of switching and Iu detection of the inverter circuit 14.

  FIG. 6 is an example of avoiding interference noise by correcting the timing of current detection. By performing the Iu detection of the inverter circuit 14 in the second half of the carrier period, the influence of interference noise can be avoided.

  FIG. 7 is an example of avoiding interference noise by correcting the timing of current detection. By further delaying the Iu detection of the inverter circuit 14 according to the switching timing of the IGBT 5, the influence of interference noise can be avoided.

  Note that the influence of the interference noise of the inverter circuit 14 can be avoided by the same correction method for the current detection of the power factor correction circuit 2. Needless to say, interference noise can be avoided by the same correction method even when the current detection of the inverter circuit 14 is a three-shunt method.

  The inverter control device of the present invention can prevent erroneous current detection without adding noise countermeasure components, and can provide a small and inexpensive inverter control device.

1 AC power supply 2 Power factor correction circuit 3 Diode bridge 4 Coil 5 IGBT
6 Shunt resistor 7 Diode 8 Smoothing capacitor 9 Input voltage detection circuit 10 DC voltage detection circuit 11 PFC control means 12 Input current detection circuit 13 Motor 14 Inverter circuit 15 Shunt resistance 16 Motor current detection circuit 17 Inverter control means 18 Signal correction means

Claims (1)

In an inverter control device having a power factor correction circuit, a signal correction means for correcting both or one of each switching signal and each current detection timing of the power factor improvement circuit and the inverter circuit is provided, and the signal correction means causes noise caused by switching. An inverter control device that corrects each or both of the switching signals and the current detection timing so that does not overlap with the current detection timing.