Traction motor current control apparatus

• US 4,257,092 A
• Filed: 12/13/1978
• Issued: 03/17/1981
• Est. Priority Date: 06/03/1977
• Status: Expired due to Term

• Current Assignee: ABB Daimler-Benz Transportation
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Prines, Frank J., Franz, James H., Matty, Thomas C.
• Primary Examiner(s): Smith, Jr., David
• Application Number:
  US05/968,950
• Time in Patent Office: 825 Days
• Field of Search: 318/341, 318/345 G, 318/345 C, 323/22 SC, 307/252 K, 307/252 M, 363/124
• US Class Current: 363/124
• CPC Class Codes: H02M 3/135 using semiconductor devices only
• CPC Class Codes: Y10S 388/92 Chopper

Abstract

A direct current motor power controlling chopper apparatus is disclosed which determines the operational speed of one or more traction motors propelling a passenger vehicle along a track. The speed of the motor is established by changing the ON and OFF conduction ratio or duty cycle relationship of a thyristor switch device to determine the field current and the armature voltage of that motor. The present apparatus can provide a greater controlled range of motor speeds including a lower minimum OFF operation and a full ON capacity. In addition, the present apparatus provides greater reliability due to less thermal stress on the thyristor switch devices and fewer circuit elements required to provide an improved motor current control operation.

Claims

1. In chopper apparatus operative with a direct current voltage source and having an output for controlling the energization of a load, the combination of

first controllable rectifier means connected to provide a load current path between said voltage source and said output,

conduction control means for determining the ON condition of operation of the first controllable rectifier means to supply current to said output,

commutation means for determining the OFF condition of operation of the first controllable rectifier means and including a capacitor and an inductor coupled with the first controllable rectifier means,

second controllable rectifier means connected between the voltage source and said capacitor for providing a first direction voltage charge to said capacitor, and

charging means operative with said first controllable rectifier means and connected with said capacitor and said voltage source for providing a current path to maintain a predetermined second direction voltage charge of said capacitor in relation to said voltage source.

2. The chopper apparatus of claim 1, with said charging means maintaining said second direction voltage charge by current flow through the first controllable rectifier means during said ON condition of operation of said first controllable rectifier means of the chopper apparatus.

3. The chopper apparatus of claim 1, with said charging means including a diode clamp being operative to hold the voltage charge on said capacitor to a substantially fixed value in relation to a given voltage source.

4. In load energization control apparatus operative with a voltage source and having an output for energizing a load, the combination of

first means connected to provide current to said load through a path between said voltage source and said output,

second means connected to initiate the current conduction of said first means to supply current to said output,

third means connected to terminate the current conduction of said first means and including a capacitor coupled with said first means,

fourth means connected across said output and responsive to current provided by said first means for holding a predetermined voltage charge to said capacitor,

fifth means including a diode and an inductor connected across said output for providing a load current path when the current conduction of said first means is terminated,

with said capacitor being connected to provide a conductive path for the reverse recovery current of said diode when the current conduction of said first means is initiated.

5. The load energization control apparatus of claim 4,

with said capacitor and said first means being connected to shunt said inductor when the current conduction of said first means is initiated.

6. The load energization control apparatus of claim 4,

with said capacitor and said first means being connected with said diode to limit the voltage buildup across said diode to permit said diode to recover at substantially zero voltage when the current conduction of said first means is initiated.

7. In chopper apparatus having an input for connection with a voltage source and having an output for connection to energize a load, the combination of

first means connected to establish a load current path between said input and said output and having an ON condition of operation for providing load current to said output and an OFF condition of operation,

second means including a capacitor and determining said OFF condition of operation of said first means, with said second means having an ON condition of operation for providing a first polarity voltage charge to said capacitor and an OFF condition of operation,

with said first means providing current when in said ON condition of operation to effect a second polarity voltage charge to said capacitor,

third means connected with said first means and said second means for determining the ON condition of operation of each of said first means and said second means,

with said third means determining the ON condition of operation for said first means when said capacitor is charged to said first polarity voltage and determining the ON condition of operation for said second means when said capacitor is charged to said second polarity voltage, and

fourth means connected with said capacitor for maintaining the second polarity voltage charge to said capacitor with said current provided by the ON condition of operation of said first means.

8. In chopper apparatus having an input for connection with a voltage source and having an output for connection to energize a load, the combination of

first controlled rectifier means connected to establish a first current path from said input to said output,

second controlled rectifier means including a capacitor and connected to establish a second current path from said input to said output,

with said second controlled rectifier means when conductive providing a first voltage charge on said capacitor and with said first controlled rectifier means when conductive providing a current to effect a second voltage charge on said capacitor,

control means connected with said first controlled rectifier means for determining the conduction of said first controlled rectifier means when the capacitor has said first voltage charge and connected with said second controlled rectifier means for determining the conduction of said second controlled rectifier means when the capacitor has said second voltage charge, and

means including a resistor connected across said output for providing a charging current path to maintain said second voltage charge on said capacitor.

9. The chopper apparatus of claim 8, with the charging current path providing means including said resistor having a predetermined value in relation to continuing the conduction of the second controlled rectifier means as determined by said control means.

11. The chopper apparatus of claim 8, with said fourth means includingsaid resistor connected in series with said capacitor and across said output for determining the voltage charge of said capacitor when said first controlled rectifier means is conductive.

10. The chopper apparatus of claim 10, with said fourth means including said resistor connected in series with said capacitor for determining the voltage charge on said capacitor when the first controlled rectifier means is conductive.

12. In chopper apparatus operative with a direct current voltage source and having an output for controlling the energization of a load, the combination of

first controllable rectifier means connected to provide a load current path between said voltage source and said output,

conduction control means for determining the ON condition of operation of the first controllable rectifier means to supply current to said output,

commutation means for determining the OFF condition of operation of the first controllable rectifier means and including a capacitor and an inductor coupled with the first controllable rectifier means,

second controllable rectifier means connected between the voltage source and said capacitor and having an ON condition of operation for providing a voltage charge to said capacitor, and

means including a resistor connected with said second controllable rectifier and said voltage source for providing a holding current for maintaining the ON condition of operation of the second controllable rectifier means limiting the rate of change of current through at least one of said first and second controllable rectifier means.