JP2005354792A - Power feed circuit for inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power feed circuit for an inverter device having both stable operation and reliability. <P>SOLUTION: The power feed circuit 10 includes: a triangular wave oscillator 12 that outputs a triangular wave; a soft start circuit 14 that outputs a waveform inclined in rising and falling; a PWM (pulse width modulation) circuit 16 that is inputted with outputs of the triangular wave oscillator 12 and the soft start circuit 14, and outputs a pulse while changing a duty ratio; and a IPM (intelligent power module) 22 that makes a power supply current pass while switching-operating the current by an output of the PWM circuit 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply circuit that supplies power to a large-capacitance capacitor provided in an inverter device.

Urban transportation systems such as monorails and astrums are driven by induction motors. As shown in FIG. 3, a high-speed switching type power element such as an IGBT (insulated gate bipolar transistor) 34 is used as the drive circuit 38 of the induction motor 36 in the recent urban traffic system. The induction motor 36 is inverter-controlled by the switching operation of the IGBT 34.

  In order to stably operate the surge generated by the IGBT 34 in the inverter device 32 during the switching operation, it is important to effectively arrange a large-capacitance capacitor C in the inverter device 32. As the capacitor C, an electrolytic capacitor is generally used.

  In order to open and close the primary power supply of the inverter device 32 including the capacitor C as a main power filter, first, the precharge contactor MCR is turned on, and the capacitor C of the inverter device 32 is precharged via the resistor R1. When the charging voltage of the capacitor C gradually becomes about 70% to 80% of the voltage of the primary power supply (DC 600V overhead wire), the main contactor (electromagnetic contactor) MC is turned on.

  When the main contactor MC is turned on all at once without performing the above precharge operation, the no-fuse breaker NFB is tripped (cut off) by the overcurrent holding operation due to the inrush current to the capacitor C, or the main contactor MC This causes problems such as welding of contact points.

Moreover, a large space is required as the main contactor MC, and a precharging circuit that requires a heat radiation space is required. Mechanical life is short due to opening / closing operation fatigue. The electrical life is short due to deterioration caused by energization and arc discharge. The opening / closing operation time is long (about 5 seconds) and the opening / closing operation sound is loud. The actual price is as high as 100,000 yen or more. The operation reliability is low, the response is slow and cannot be protected when the IGBT is abnormal, and maintenance is required. As described above, the circuit of FIG. 3 has many drawbacks.
Japanese Patent Laid-Open No. 10-271849

  An object of the present invention is to provide a power supply circuit for an inverter device having stable operation and reliability.

  The gist of the power supply circuit of the present invention is a power supply circuit for supplying power from an electric power source to an inverter device, which is a triangular wave oscillator that outputs a triangular wave and software that outputs a pulse having a waveform with rising and falling slopes. A start circuit, a PWM circuit that receives outputs of the triangular wave oscillator and the soft start circuit, outputs a pulse while changing a duty ratio, and an IPM that passes a power supply current while performing a switching operation using the output of the PWM circuit. Including.

  An inductance that smoothes the current that has passed through the IPM, and an FRD that supplies power to the inverter device with a counter electromotive force of the inductance when the IPM is off.

  When the operation of the IPM is abnormal, a circuit that generates an abnormal pulse in the IPM, a latch circuit that receives the abnormal pulse and outputs a low level when the abnormal pulse is input, and outputs from the PWM and the latch circuit AND circuit to which is inputted.

  According to the present invention, since the electrical switching operation of the IPM is used instead of turning the mechanical switch on and off, there is no noise or mechanical deterioration generated by the apparatus, and the operation reliability is high. There is no electricity or arc discharge, and there is no electrical life degradation. Since it is an electrical switching operation, the switching operation time is also short. Since abnormality is detected in the IPM, protection reliability is high and maintenance is not required.

  Next, embodiments of the present invention will be described with reference to the drawings. The power supply circuit of the present invention is a part of the drive circuit of the induction motor, and supplies power to the inverter device of this drive circuit. The power supply circuit 10 shown in FIG. 1 is connected to the inverter device 32 shown in FIG.

The power supply circuit 10 of the present invention shown in FIG. 1 includes a triangular wave oscillator 12 that outputs a triangular wave, a soft start circuit 14 that outputs pulses having waveforms with rising and falling slopes, and a triangular wave oscillator 12 and a soft start circuit 14. A PWM (pulse width modulation) circuit 16 that outputs an input and outputs a pulse while changing a duty ratio, and an IPM (interigent) that allows a power supply current to pass through while performing a switching operation with the output of the PWM circuit 16
power module) 22.

  The triangular wave generated by the triangular wave oscillator 12 serves as a carrier when the PWM circuit 16 performs PWM.

  The soft start circuit 14 oscillates a waveform with rising and falling slopes when a start signal is input. The pulse output from the soft start circuit 14 is a driver signal for calculation in the PWM circuit 16.

  In the present invention, the activation signal is input to the soft start circuit 14 by a sequencer or the like.

PWM circuit 16, by comparing the output from the triangular wave oscillator 12 and a soft-start circuit 14, and FIG. 2 (b) to indicate like _{T on:} the circuit for outputting a pulse while changing the duty ratio determined by the _{T off} is there. The degree of change in the duty ratio varies depending on the rising slope of the pulse output from the soft start circuit 14.

  The IPM 22 is obtained by adding various self-diagnosis and protection functions to the IGBT 24. The IGBT 24 of the IPM 22 performs a switching operation by a pulse from the PWM circuit 16. As shown in FIG. 2B, the pulse from the PWM circuit 16 gradually increases in pulse width and eventually turns on. Therefore, in the switching operation of the IGBT 24, the ON state in a certain period gradually becomes longer and eventually becomes the all ON state.

  The present invention also includes an inductance L for smoothing the current that has passed through the IPM 22, and an FRD (fast recovery diode) for supplying power to the capacitor C of the inverter device 32 with a counter electromotive force of the inductance L when the IPM 22 is off. ) And.

  Various self-diagnosis and protection functions of the IPM 22 include a circuit that generates an abnormal pulse in the IPM 22 when the operation of the IPM 22 is abnormal. The contents detected by the IPM 22 as abnormal operation are overcurrent, overheating, and power supply voltage abnormality.

  Furthermore, the present invention provides a latch circuit 28 that outputs an abnormal pulse after an abnormality is detected, and outputs a low level when the abnormal pulse is input. ,including.

  Insulating elements 20 and 26 shown in FIG. 1 use photocouplers. In the photocoupler, the light-emitting diode and the light-receiving element are electrically insulated and can be incorporated into one container. Therefore, the photocoupler can be used as a coupling between circuits having different voltages or as a high-breakdown-voltage switching element.

  Next, a method of supplying power to the inverter device 32 of FIG. 3 using the circuit 10 of FIG. 1 will be described. The power source is the same DC power source as in FIG.

  (1) A start signal is input to the soft start circuit 14 from a sequencer or the like. The soft start circuit 14 outputs an output waveform e whose rising edge is inclined when the activation signal is input.

  (2) The triangular wave generator 12 oscillates and outputs a triangular wave.

  (3) The PWM circuit 16 compares the output e of the soft start circuit 14 with the triangular wave d as shown in FIG. As a result of the comparison, a pulse f subjected to pulse width modulation is output as shown in FIG. In FIGS. 2A and 2B, the horizontal axis represents time, and the vertical axis represents voltage.

  (4) The pulse-width-modulated output passes through the AND circuit 18 and is further insulated by the photocoupler 20 and then input to the IPM 22 as the gate signal of the IPM 22.

(5) The IGBT 24 of the IPM 22 is turned on by a pulse from the PWM circuit 16. A current I ₁ flows to the inductance L through the IGBT 24. As shown in FIG. 2C, a current I ₁ flows from the inductance L to the inverter device 32.

(6) When the IGBT 24 is turned off, the current I ₂ flows from the FRD through the inductance L to the inverter device 32 due to the counter electromotive force of the inductance L.

  The current output as shown in FIG. 3C is due to the current smoothing operation of the inductance L in the steps (5) and (6).

  (7) As shown in FIG. 3C, the current supplied to the inverter device 32 gradually increases. Therefore, the capacitor C of the inverter device 32 is gradually precharged. The preliminary charging of the capacitor C is, for example, within 100 ms.

  (8) After the capacitor C is precharged, the duty ratio of the pulse from the PWM circuit 16 becomes 100%. Therefore, the IGBT 24 is fully turned on.

  The steps (5) to (7) correspond to the opening and closing of the precharging contactor MCR shown in the prior art. The step (8) corresponds to the ON operation of the main contactor MC shown in the prior art. According to the present invention, since the capacitor C is charged by the electrical switching operation of the IGBT, there are no disadvantages of noise and short life due to mechanical switching as in the prior art.

  When the self-diagnosis function of the IPM 22 detects an abnormality such as an overcurrent, the protection function of the IPM 22 is activated. The IPM 22 oscillates an abnormal pulse, and the pulse is input to the latch circuit 28. The output of the latch circuit 28 becomes low level, and the output is input to the AND circuit 18. Since a low level input is generated in the AND circuit 18, the output from the AND circuit 18 is constant at a low level regardless of the output from the PWM circuit 18.

  Due to the self-diagnosis function of the IPM 22, the IPM 22 operates within the allowable current range. Therefore, the power supply circuit 10 of the present invention is highly reliable and has a long life.

  Note that the output of the latch circuit 28 can be returned to the high level by inputting an abnormal reset signal to the latch circuit 28 after the output of the latch circuit 28 becomes the low level. When the output of the latch circuit 28 returns to the high level, the output of the PWM circuit 16 can pass through the AND circuit 18.

  By changing from the circuit 30 in FIG. 3 to the circuit 10 in FIG. 1, the number of times of switching of the precharge contactor MCR is limited to about 100,000 times. There is no need to consider. Conventionally, about 5 seconds were required for preliminary charging, but in the case of the present invention, the time is about 100 milliseconds. Conventionally, it is a mechanical operation and switching is noisy, but the present invention is silent because it performs electrical switching. Conventionally, a switch or the like is a long-life product, and the circuit is not protected, so that periodic replacement is necessary. However, the present invention is maintenance-free due to the protection function of the IPM. Furthermore, if it is this invention, it will become space saving and a low price compared with the past.

  As mentioned above, although embodiment was described about this invention, this invention is not limited to said embodiment. In addition, the present invention can be implemented with various improvements, modifications, and changes based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

It is a figure which shows the circuit structure of the electric power supply circuit which concerns on this invention. It is a figure which shows supply of the electric current to an inverter apparatus, (a) is a figure which shows the relationship between the triangular wave input into a PWM circuit, and a driver signal, (b) is a figure which shows the pulse output from a PWM circuit. (C) is a figure which shows the electric current supplied to an inverter. It is a figure which shows the circuit structure of the conventional power supply circuit.

Explanation of symbols

10, 30: Power supply circuit 12: Triangular wave generator 14: Soft start circuit 16: PWM circuit 18: AND circuit 20, 26: Insulating element (photocoupler)
22: IPM
24, 34: IGBT
28: Latch circuit 36: Induction motor 38: Drive circuit

Claims (3)

A power supply circuit for supplying power from a power source to an inverter device,
A triangular wave oscillator that outputs a triangular wave;
A soft-start circuit that outputs waveforms with rising and falling slopes;
PWM circuit that receives the output of the triangular wave oscillator and the soft start circuit and outputs a pulse while changing the duty ratio;
An IPM that allows a power supply current to pass while performing a switching operation with the output of the PWM circuit;
Including power supply circuit. An inductance for smoothing the current passed through the IPM;
FRD for supplying power to the inverter device with a counter electromotive force of inductance when the IPM is off;
The power supply circuit according to claim 1, comprising: A circuit for generating an abnormal pulse in the IPM when the IPM operates abnormally;
A latch circuit that receives the abnormal pulse and outputs a low level when the abnormal pulse is input;
An AND circuit to which the output from the PWM and the latch circuit is input;
The power supply circuit according to claim 1, comprising:

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