Pwm cycloconverter and power fault detector

• US 20030052544A1
• Filed: 09/05/2002
• Published: 03/20/2003
• Est. Priority Date: 03/08/2000
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Yaskawa Denki
• Original Assignee: Kabushiki Kaisha Yaskawa Denki
• Inventors: Tanaka, Koji, Yamasaki, Tetsuya, Ishii, Sadao, Watanabe, Eiji, Hara, Hidenori, Yamamoto, Eiji
• Application Number:
  US10/221,246
• Publication Number:
  US 20030052544A1
• Time in Patent Office: Days
• US Class Current: 307/66
• CPC Class Codes: B66B 5/0018 Devices monitoring the operating condition of the elevator system
• CPC Class Codes: B66B 5/02 responsive to abnormal operating conditions
• CPC Class Codes: H02M 5/271 from a three phase input voltage
• CPC Class Codes: H02M 5/273 with digital control
• CPC Class Codes: H02M 7/53876 based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times
• CPC Class Codes: H02P 27/16 using ac to ac converters without intermediate conversion to dc H02P27/05 takes precedence

Abstract

A PWM cycloconverter is disclosed that can switch power supplies without interrupting operation in the event of a power supply abnormality. When a power supply abnormality occurs in three-phase AC power supply 1, power supply abnormality detection circuit 30 outputs power supply abnormality detection signal 120, whereby power supply switch 20 selects and outputs the output voltage of uninterruptible power supply 10. Phase detection circuit switch 43 selects and outputs phase information that is output from uninterruptible power supply phase detection circuit 41. Uninterruptible power supply phase detection circuit 41 detects the phase of uninterruptible power supply 10 from before the occurrence of the power supply abnormality, whereby accurate phase information of uninterruptible power supply 10 can be output even immediately after phase detection circuit switch 43 switches the phase information that is output. As a result, operation is not interrupted when switching power supplies.

Claims

1. A PWM cycloconverter including:

a bidirectional switch module that is constituted by nine bidirectional switches for connecting between each of voltages of three phases of a three-phase AC power supply and output voltages of three phases; and

an input power supply phase detection circuit for receiving as input two phases of the AC voltages of three phases that are applied as input to said bidirectional switch module and detecting the phase of this input,

characterized in that it includes;

an uninterruptible power supply, which is a single-phase AC power supply;

a power supply abnormality detection circuit for outputting a power supply abnormality detection signal when a power supply abnormality of said three-phase AC power supply has been detected;

a power supply switch for outputting the output voltages of three phases from said three-phase AC power supply to said bidirectional switch module when said power supply abnormality detection signal is not received as input, and, when said power supply abnormality detection signal is received, outputting single-phase AC voltage from said uninterruptible power supply to said bidirectional switch module in place of the output voltages of two phases for which said input power supply phase detection circuit detects phase; and

a control unit for controlling said bidirectional switch module based on phase information that has been detected by said input power supply phase detection circuit, implementing control such that said bidirectional switch module operates under three-phase input when said power supply abnormality detection signal is not received as input, and switching the control mode of said bidirectional switch module from three-phase input operation to single-phase input operation when said power supply abnormality detection signal is received.

2. A PWM cycloconverter including:

a bidirectional switch module that is constituted by nine bidirectional switches for connecting between each of voltages of three phases of a three-phase AC power supply and output voltages of three phases; and

an input power supply phase detection circuit for receiving as input two phases of the AC voltages of three phases that are applied as input to said bidirectional switch module and detecting the phase, of this input,

characterized in that it includes;

an uninterruptible power supply, which is a single-phase AC power supply;

a power supply abnormality detection circuit for outputting a power supply abnormality detection signal when a power supply abnormality of said three-phase AC power supply has been detected;

a power supply switch for outputting the output voltages of three phases from said three-phase AC power supply to said bidirectional switch module when said power supply abnormality detection signal is not received as input, and, when said power supply abnormality detection signal is received, outputting single-phase AC voltage from said uninterruptible power supply to said bidirectional switch module in place of the output voltages of two phases for which said input power supply phase detection circuit detects phase;

an uninterruptible power supply phase detection circuit for detecting the phase of said uninterruptible power supply;

a phase detection circuit switch for selecting and outputting phase information that is output from said uninterruptible power supply phase detection circuit when said power supply abnormality detection signal is received as input and selecting and outputting phase information that is output from said input power supply phase detection circuit when said power supply abnormality detection signal is not received; and

a control unit for controlling said bidirectional switch module based on phase information that has been output by said phase detection circuit switch, implementing control such that said bidirectional switch module operates under three-phase input when said power supply abnormality detection signal is not received as input, and switching the control mode of said bidirectional switch module from three-phase input operation to single-phase input operation when said power supply abnormality detection signal is received.

3. A PWM cycloconverter including:

a bidirectional switch module that is constituted by nine bidirectional switches for connecting between each of voltages of three phases of a three-phase AC power supply and output voltages of three phases; and

an input power supply phase detection circuit for receiving as input two phases of the AC voltages of three phases that are applied as input to said bidirectional switch module and detecting the phase of this input,

characterized in that it includes;

a DC power supply;

a power supply abnormality detection circuit for outputting a power supply abnormality detection signal when a power supply abnormality of said three-phase AC power supply has been detected;

a power supply switch for outputting the output voltages of three phases from said three-phase AC power supply to said bidirectional switch module when said power supply abnormality detection signal is not received as input, and, when said power supply abnormality detection signal is received, outputting DC voltage from said DC power supply to said bidirectional switch module in place of the output voltages of two phases for which said input power supply phase detection circuit detects phase;

a fixed phase information generation circuit;

a phase detection circuit switch for selecting and outputting fixed phase information that is output from said fixed phase information generation circuit when said power supply abnormality detection signal is received as input, and selecting and outputting phase information that is output from said input power supply phase detection circuit when said power supply abnormality detection signal is not received; and

a control unit for controlling said bidirectional switch module based on phase information that has been output by said phase detection circuit switch, implementing control such that said bidirectional switch module operates under three-phase input when said power supply abnormality detection signal is not received as input, and switching the control mode of said bidirectional switch module from three-phase input operation to single-phase input operation when said power supply abnormality detection signal is received.

4. A PWM cycloconverter including:

a bidirectional switch module that is constituted by nine bidirectional switches for connecting between each of voltages of three phases of a three-phase AC power supply and output voltages of three phases;

an input power supply phase detection circuit for receiving as input two phases of the three phases of AC voltages that are applied as input to said bidirectional switch module and detecting the phase of this input; and

a control unit for controlling said bidirectional switch module based on phase information that is detected by means of said input power supply phase detection circuit,

characterized in that it includes;

a power supply abnormality detection circuit for outputting a power supply abnormality detection signal and a switch control signal when a power supply abnormality of the three-phase AC power supply has been detected, halting the output of said power supply abnormality detection signal when the power supply abnormality has been restored to normal, and, after the subsequent passage of a fixed time interval, halting the output of said switch control signal;

an uninterruptible power supply module for generating voltages of three phases that are synchronized with the output voltages of said three-phase AC power supply by constantly detecting the phase of said three-phase AC power supply, and, when said power supply abnormality detection signal has been received as input, for outputting voltages of three phases at a fixed cycle based on phase information that immediately precedes input of said power supply abnormality detection signal; and

a power supply switch for outputting the output voltages of three phases from said three-phase AC power supply to said bidirectional switch module when said switch control signal is not received as input, and, when said switch control signal is received, outputting output voltages of three phases from said uninterruptible power supply module to said bidirectional switch module.

5. A PWM cycloconverter according to claim 4, wherein said uninterruptible

power supply is constituted by a PWM inverter.

6. An elevator driver that is constituted by a PWM cycloconverter having:

a bidirectional switch module that is constituted by nine bidirectional switches for connecting between each of voltages of three phases of a three-phase AC power supply and output voltages of three phases; and

an input power supply phase detection circuit for receiving as input two phases of the AC voltages of three phases that are applied as input to said bidirectional switch module and detecting the phase of this input,

characterized in that it includes;

a power supply abnormality detection circuit for outputting a power supply abnormality detection signal when a power supply abnormality in said three-phase AC power supply has been detected;

a power supply switch for outputting output voltages of three phases from said three-phase AC power supply to said bidirectional switch module when said power supply abnormality detection signal is not received as input, and, when said power supply abnormality detection signal is received, outputting the output voltage of a power supply that is set as the emergency power supply to said bidirectional switch module;

an emergency power supply phase detection circuit for detecting the phase of said emergency power supply;

a fixed phase information generation circuit for generating and outputting fixed phase information;

a phase detection circuit switch setting unit for selecting and outputting in accordance with settings that have been made beforehand either phase information from said emergency power supply phase detection circuit or fixed phase information from said fixed phase information generation circuit;

a phase detection circuit switch for selecting and outputting phase information that is output from said phase detection circuit switch setting unit when said power supply abnormality detection signal is received as input, and for selecting and outputting phase information that is output from said input power supply phase detection circuit when said power supply abnormality detection signal is not received as input; and

a control unit for controlling said bidirectional switch module based on phase information that has been output from said phase detection circuit switch, implementing control such that said bidirectional switch module operates under three-phase input when said power supply abnormality detection signal is not received as input, and switching the control mode of said bidirectional switch module from three-phase input operation to operation of the control mode that accords with phase information that is output from said phase detection circuit switch when said power supply abnormality detection signal is received as input.

8. An elevator driver according to claim 6 or claim 7, wherein said emergency power supply is any one power supply selected from a three-phase AC power supply, a single-phase AC power supply, and a DC power supply.

7. An elevator driver that is constituted by a PWM cycloconverter having:

a bidirectional switch module that is constituted by nine bidirectional switches for connecting between output voltages of three phases and either voltages of three phases of a three-phase AC power supply or output voltage from an emergency power supply that has been selected by a power supply switch that is connected to the outside; and

an input power supply phase detection circuit for receiving as input two phases of AC voltages of three phases that are applied as input to said bidirectional switch module and detecting the phase of this input,

characterized in that it includes;

a power supply abnormality detection circuit for outputting a power supply abnormality detection signal when a power supply abnormality in said three-phase AC power supply has been detected;

an emergency power supply phase detection circuit for detecting the phase of said emergency power supply;

a fixed phase information generation circuit for generating and outputting fixed phase information;

a phase detection circuit switch setting unit for selecting and outputting in accordance with settings that have been made beforehand either phase information from said emergency power supply phase detection circuit or fixed phase information from said fixed phase information generation circuit;

a phase detection circuit switch for selecting and outputting phase information that is output from said phase detection circuit switch setting unit when said power supply abnormality detection signal is received as input, and for selecting and outputting phase information that is output from said input power supply phase detection circuit when said power supply abnormality detection signal is not received as input; and

a control unit for controlling said bidirectional switch module based on phase information that has been output from said phase detection circuit switch, implementing control such that said bidirectional switch module operates under three-phase input when said power supply abnormality detection signal is not received as input, and switching the control mode of said bidirectional switch module from three-phase input operation to operation of the control mode that accords with phase information that is output from said phase detection circuit switch when said power supply abnormality detection signal is received as input.

9. An elevator driver that is constituted by a PWM cycloconverter having:

a bidirectional switch module that is constituted by nine bidirectional switches for connecting between each of voltages of three phases of a three-phase AC power supply and output voltages of three phases; and

an input power supply phase detection circuit for receiving as input two phases of AC voltages of three phases that are applied as input to said bidirectional switch module and detecting the phase of this input,

characterized in that it includes;

a power supply abnormality detection circuit for outputting a power supply abnormality detection signal when a power supply abnormality in said three-phase AC power supply has been detected;

a power supply switch for outputting output voltages of three phases from said three-phase AC power supply to said bidirectional switch module when said power supply abnormality detection signal is not received as input, and for outputting output voltages of an emergency three-phase AC power supply that is set as the emergency power supply to said bidirectional switch module when said power supply abnormality detection signal is received as input;

an emergency power supply phase detection circuit for detecting the phase of said emergency three-phase AC power supply;

a phase detection circuit switch for selecting and outputting phase information that is output from said emergency power supply phase detection circuit when said power supply abnormality detection signal is received as input, and for selecting and outputting phase information that is output from said input power supply phase detection circuit when said power supply abnormality detection signal is not received as input; and

a control unit for implementing control such that said bidirectional switch module operates under three-phase input based on phase information that is output from said phase detection circuit switch.

10. A power supply abnormality detection circuit for detecting abnormalities of power supply voltage of a three-phase AC power supply, comprising:

a power supply voltage information generation circuit for detecting information that corresponds to the size relation of the voltages of each phase of said three-phase AC power supply and outputting this information as a power supply voltage information signal;

an abnormality detection signal generation circuit for holding in advance information that is based on the size relations of the voltages of each phase when said three-phase AC power supply is normal, synchronizing the information with the output voltages of said three-phase AC power supply, and outputting this information as an abnormality detection signal; and

a determination circuit for comparing said power supply voltage information signal with said abnormality detection signal at fixed time intervals and outputting a power supply voltage abnormality signal when these signals differ.

11. A power supply abnormality detection circuit according to claim 10, wherein said determination circuit is constituted by:

a plurality of exclusive-OR circuits for carrying out exclusive-OR calculation of said abnormality detection signal and said power supply voltage information signal and outputting the calculation results;

an OR circuit for carrying out OR calculation of each output of said plurality of exclusive-OR circuits and outputting the calculation results; and

a flip-flop circuit for holding the output value of said OR circuit for a fixed time interval and outputting said output value as said power supply voltage abnormality detection signal.

12. A power supply abnormality detection circuit according to claim 10 or claim 11, wherein information that is indicated by said power supply voltage information signal is information indicating which of the voltage values of each phase is the highest;

and information indicating which of the voltage values of each phase is the lowest.

13. A power supply voltage abnormality detection method for detecting abnormalities of power supply voltages of a three-phase AC power supply;

said method comprising steps of;

holding in advance information that is based on size relations of voltage values of each phase when said three-phase AC power supply is normal as abnormality detection information;

detecting information that corresponds to the size relations of voltage values of each phase of said three-phase AC power supply as power supply voltage information; and

comparing, at fixed time intervals, said power supply voltage information and, of said abnormality detection signal, abnormality detection information that corresponds to the timing of obtaining said power supply voltage information, and determining that a power supply voltage abnormality has occurred when this information differs.

14. An AC/AC direct power converter, comprising:

an input filter for shaping the output waveforms of the three phases of a three-phase AC power supply;

a plurality of bidirectional switches that are connected to signals of three phases that have been wave-shaped by said input filter for effecting power conversion by means of ON/OFF operation;

a PWM control circuit for implementing ON/OFF control of said bidirectional switches based on a voltage commanded and a frequency command;

a commutation control circuit for controlling commutation of said bidirectional switches;

a voltage detection circuit for detecting and outputting the three line voltages of said three-phase AC power supply;

a maximum voltage generation circuit for generating the maximum line voltage from said line voltages; and

a control circuit for commanding a voltage to said PWM control circuit such that the three-phase output is always equal to or less than said maximum line voltage.

15. An AC/AC direct power converter according to claim 14, wherein:

said maximum voltage generation circuit is constituted by;

a rectifying circuit for rectifying said line voltages and

a multiplier for prescribed multiplication of the output of said rectifying circuit; and

said control circuit is constituted by;

a voltage command unit for commanding a desired voltage and

a comparator for comparing the output of said multiplier and the voltage command of said voltage command unit and outputting the smaller of the two.

16. An AC/AC direct power converter, comprising:

an input filter for shaping the output waveforms of three phases of a three-phase AC power supply;

a plurality of bidirectional switches that are connected to signals of three phases that have been wave-shaped by said input filter for effecting power conversion by means of ON/OFF operation;

a PWM control circuit for implementing ON/OFF control of said bidirectional switches based on a voltage command and a frequency command;

a commutation control circuit for controlling commutation of said bidirectional switches;

a voltage detection circuit for detecting and outputting the three line voltages of said three-phase AC power supply;

a maximum voltage generation circuit for generating the maximum line voltage from said line voltages; and

a control circuit for commanding a voltage and frequency to said PWM control circuit such that the output is always equal to or less than said maximum line voltage.

17. An AC/AC direct power converter according to claim 16, wherein:

said maximum voltage generation circuit is constituted by;

a rectifying circuit for rectifying said line voltages, and

a multiplier for prescribed multiplication of the output of said rectifying circuit; and

said control circuit is constituted by;

a voltage command unit for commanding a desired voltage;

a first comparator for comparing the output voltage of said multiplier and the voltage command of said voltage command unit and outputting the smaller of the two;

a frequency command unit for commanding a desired frequency;

a function generator for computing the maximum frequency that can be obtained as the three-phase output from the output of said multiplier; and

a second comparator for comparing the frequency that is computed by said function generator and the frequency command of said frequency command unit and outputting the smaller of the two.

18. An AC/AC direct power converter, comprising;

an input filter for shaping output waveforms of the three phases of a three-phase AC power supply;

a plurality of bidirectional switches that are connected to signals of three phases that have been wave-shaped by said input filter for effecting power conversion by means of ON/OFF operation;

a PWM control circuit for implementing ON/OFF control of said bidirectional switches based on a voltage command and a frequency command;

a commutation control circuit for controlling commutation of said bidirectional switches;

a voltage detection circuit for detecting and outputting the three line voltages of said three-phase AC power supply;

a maximum voltage generation circuit for generating the maximum line voltage from said line voltages; and

a control circuit for commanding a speed and a magnetic flux to said PWM control circuit such that the terminal voltage of a motor that is connected to the output is always equal to or less than said maximum line voltage.

19. An AC/AC direct power converter according to claim 18, wherein:

said maximum voltage generation circuit is constituted by;

a rectifying circuit for rectifying said line voltages, and

a multiplier for prescribed multiplication of the output of said rectifying circuit;

and said control circuit is constituted by;

a speed command unit for commanding a desired speed,

a first function generator for computing the maximum speed that can be obtained as the three-phase output from the output of said multiplier,

a first comparator for comparing said maximum speed and the commanded speed of said speed command unit and outputting the smaller of the two,

a magnetic flux command unit for commanding a desired magnetic flux,

a second function generator for computing the maximum magnetic flux that the three-phase output can give to said motor from the output of said multiplier, and

a second comparator for comparing said maximum magnetic flux and the command of said magnetic flux command unit and outputting the smaller of the two.

20. An AC/AC direct power converter according to claim 19, wherein:

said first function generator commands a predetermined minimum speed when said maximum line voltage falls below a prescribed value; and

said second function generator commands a predetermined minimum magnetic flux when said maximum line voltage falls below a prescribed value.