Pulse width logic/power isolation circuit

• US 4,777,382 A
• Filed: 06/19/1987
• Issued: 10/11/1988
• Est. Priority Date: 06/19/1987
• Status: Expired due to Term

• Current Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Original Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Inventors: Reingold, Phillip S.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Ip, Paul
• Application Number:
  US07/064,905
• Time in Patent Office: 480 Days
• Field of Search: 307/7, 307/106, 307/107, 307/108, 307/109, 307/419, 307/412, 307/413, 307/414, 307/415, 307/416, 307/417, 307/418, 307/420, 307/421, 307/282, 307/265, 307/266, 307/267 , 307/268, 307/595, 318/503, 318/439, 318/605, 318/606, 318/608, 318/678, 318/681, 318/762, 318/701, 318/721, 318/798, 318/599, 318/802, 318/800, 318/803, 318/805, 318/806, 318/808, 318/810 , 318/811, 318/812, 318/254, 318/138, 318/621, 363/41, 363/28, 363/124, 363/126, 363/46, 363/48, 363/87, 363/59, 363/43, 363/96, 363/98, 328/58, 328/65
• US Class Current: 307/106
• CPC Class Codes: H03K 17/567 Circuits characterised by the use of more than one type of semiconductor device, e.g. BIMOS, composite devices such as IGBT
• CPC Class Codes: H03K 17/601 using transformer coupling H03K17/61 takes precedence
• CPC Class Codes: H03K 17/691 using transformer coupling

Abstract

A circuit is disclosed which provides power isolation between the initializing and driven circuit, allowing the logic of a wide pulse width signal to be effectively transmitted across pulse transformers and faithfully reproduced.

Claims

1. A variable pulse width transmitting isolation circuit comprising:

means for receiving a variable pulse width signal and transmitting a first pulse of short duration when said received signal assumes a positive voltage potential and transmitting a second pulse of short duration when said received signal assumes a zero voltage potential;

inductive transmission means, attached to said means for receiving, for inductively transmitting said first and said second pulse of short duration; and

switching means, having an output, connected to said inductive transmission means, for assuming a first preselected voltage potential at said output upon receipt of said first pulse of short duration and for maintaining said first preselected voltage potential at said output until said second pulse of short duration is received, and then for assuming and maintaining a second preselected voltage potential until receipt of said first pulse of short duration.

2. The variable pulse width transmitting isolation circuit of claim 1 wherein said means for receiving further comprises a digital logic circuit having one input to receive the variable pulse width signal, a first pair of outputs, a second pair of outputs, and a timing capacitor, connected to said digital logic circuit, responsive to the variable pulse width signal received at said input of said means for receiving to govern the duration of said first and said second pulse of short duration.

3. A pulse transmission isolation circuit comprising:

a unipolar pulse generator having a first pulse source for indicating a high potential, and a second pulse source for indicating a low potential;

a first pulse transformer connected to said first pulse source;

a second pulse transformer connected to said second pulse source; and

switching means connected to said first and said second pulse transformers to transmit a signal having a relatively high voltage during and after a pulse is received through said first pulse transformer, and a relatively low voltage during and after a pulse is received through said second pulse transformer.

4. A variable pulse width signal transmission/isolation circuit comprising:

a pulse generator adapted to recive a variable pulse width input signal and to generate and transmit a first short duration pulse signal when said input signal translates from a lower value to a higher value, and to generate and transmit a second short duration pulse signal when said input signal translates from a higher value to a lower value;

a first pulse transformer, having first and second output leads, connected to said pulse generator to receive and inductively transmit said first short duration pulse signal;

a second pulse transformer, having first and second output leads, connected to said pulse generator to receive and inductively transmit said second short duration pulse signal;

a switching circuit connected to said first and second output leads of said first and second pulse transformers, said switching circuit generating an output signal having a first voltage value when said first short duration pulse signal is received, and generating a second voltage value when said second short duration pulse signal is received.

5. A variable pulse width signal transmission/isolation circuit comprising:

a pulse generator adapted to receive a variable pulse with input signal and to generate and transmit a first short duration pulse signal when said input signal translates from a lower value to a higher value, and to generate and transmit a second short duration pulse signal when said input signal translates from a higher value to a lower value;

a first pulse transformer, having first and second output leads, connected to said pulse generatior to receive and inductively transmit said first short duration pulse signal;

a second pulse transformer, having first and second output leads, connected to said pulse generator to receive and inductively transmit said second short duration pulse signal;

a switching circuit for generating an output signal initiated in resposne to said first short duration pulse signal and terminated in response to said second short duration pulse signal whereby the width of said output signal is the same as the width of said input signal.

6. A pulse signal detection circuit comprising:

means for receiving an input pulse; and

means for outputting a short duration pulse, connected to said means for receiving, having a first output for outputting a short duration pulse when the receipt of an input pulse begins, and a second output for outputting a short duration pulse when the receipt of an input pulse ends.

7. The pulse signal detector circuit of claim 6 further comprising:

inductive transmission means, attached to said first and said second outputs for inductively receiving and retransmitting said short duration pulses, to conductively isolate said pulse signal detector circuit while allowing transmission of said short duration pulses.

8. Apparatus for generating a variable width, relatively high power electrical pulse output signal corresponding to a variable width pulse control signal, having a relatively low voltage base potential comprising:

a pulse generation circuit having an input receiving said control signal and operable to generate first and second short duration pulses, having a relatively low voltage base potential, corresponding to the initiation and the completion respectively of said control signal;

a first inductive transformer receiving said first short duration pulse and operable to inductively generate a coresponding first, short duration, pulse output signal, having a relatively high voltage base potential, indicative of said initiation of the control signal;

a second inductive transformer receiving said second short duration pulse and operable to inductively generate a coresponding second, short duration pulse output signal, having a relatively high voltage base potential, indicative of said completion of the control signal; and

a circuit receiving said first and second output signals and operable in response thereto, to generate a relatively high power, variable pulse width output signal whose pulse width is substantially equal to the pulse width of said control signal.

9. A pulse construction circuit comprising:

an output capable of assuming a first and a second voltage potential;

first short duration pulse receiving means, connected to said output, for directing said output to assume said first voltage potential; and

second short duration pulse receiving means, connected to said output for directing said output to assume said second voltage potential.

10. The pulse construction circuit of claim 9 further comprising inductive transmission means, having an input and an output, said output connected to said first and said second pulse receiving means, for conductively isolating said first and said second pulse receiving means from said input of said inductive transmission means, wherein said input of said inductive transmission means is enabled to receive pulses for inductive transmission to said first and said second pulse receiving means.

11. A process of transmitting a variable width pulse from a low power pulse source to a higher power pulse receiver comprising the steps of:

detecting the input voltage potential of a variable width pulse;

outputting a first short duration pulse in response to the transition from a lower to a higher input voltage potential of said variable width pulse;

inductively transmitting said first short duration pulse;

outputting a high output voltage potential upon receipt of said inductively transmitted said first short duration pulse, and maintaining said high output voltage potential so long as said variable width pulse maintains a high input voltage potential;

16 outputting a second short duration pulse in response to the transition from a higher to a lower input voltage potential of said variable width pulse;

inductively transmitting said second short duration pulse; and

outputting a low output voltage potential, upon receipt of said inductively transmitted said second short duration pulse, and maintaining said low output voltage potential so long as said variable width pulse maintains a low input voltage potential.

12. The process of Step 11 wherein the magnitude of the difference between said high output voltage and said low output voltage is significantly higher than the magnitude of the difference between said high input voltage and said low input voltage.

13. The process of Step 11 wherein at least one of said output voltages are non-positive voltage.

14. A process of transmitting a variable width pulse from a low power pulse source to a higher power pulse receiver comprising the steps of:

detecting the input voltage potential of a variable width pulse;

outputting a first short duration pulse in response to the transmition from a lower to a higher input voltage potential of said variable width pulse;

inductively transmitting said first short duration pulse;

outputting a low output voltage potential, upon receipt of said inductively transmitted said first short duration pulse, and maintaining said low output voltage potential so long as said variable width pulse maintains a high input voltage potential;

outputting a second short duration pulse in response to the transition from a higher to a lower input voltage potential of said variable width pulse;

inductively transmitting said second short duration pulse; and

outputting a high output voltage potential, upon receipt of said inductively transmitted said second short duration pulse, and maintaining said high output voltage potential so long as said variable width pulse maintains a low input voltage potential.

15. A method of generating a relatively high power pulse width modulated output signal corresponding to a relatively low voltage potential pulse width modulated control signal, comprising the steps of:

generating relatively short duration, first and second pulses, of low base potential, corresponding to the initiation and completion of the control signal, respectively;

inductively transforming said first and second pulses into first and second output pulse signals of high base potential and correspondingly short duration, while isolating said low base potential from said high base potential;

initiating a relatively high power pulse width modulated output signal in response to said first output pulse signal; and

terminating said high power pulse width modulated signal in response to said second output pulse signal.

16. A commutation system for a brushless motor comprising:

means for initiating a command for motive action, having a command output, said command in the form of a command pulse delivered to said output having a width proportional to the power to be delivered to said motor;

means for receiving said command pulse, and transmitting short duration pulses in response thereto, having an input connected to said command output of means for initiating a command, and having a first output and a second output, for transmitting a short duration pulse from said first output when said command pulse begins, and transmitting a short duration pulse from said second output when said command pulse ends;

inductive coupling means, connected to said means for receiving, having a first and a second inductive outlet for coupling said short duration pulse from said first output of said means for receiving to said first inductive outlet, and for inductively coupling said short duration pulse from said second output of said means for receiving to said second inductive outlet;

switching means, attached to said inductive coupling means, having an outlet, for switching said outlet to a first predetermined voltage level upon receiving said short duration pulse from said first inductive outlet of said inductive coupling means, and for switching said outlet to a second predetermined voltage level upon receiving said short duration pulse from said second inductive outlet of said inductive coupling means;

voltage potential activated means for switching, having an activation input connected to said outlet of said switching means, and having a current input and current output terminals, said voltage potential activated means for switching to turn on current flow through said current input and output terminals when said activation input attains said first predetermined voltage level, and to shut-off current flow through said current input and output terminals when said activation input attains said second predetermined voltage level;

a power source having a voltage output connected to said current input of said voltage potential activated means for switching;

a brushless motor having an input connected to said current output of said voltage potential activated means for switching, said brushless motor powered by said power source when said means for initiating a command delivers a command pulse to said command output.

17. The system of claim 16 wherein said first predetermined voltage level is positive and said second predetermined voltage level is negative.

18. The system of claim 16 wherein said means for initiating a command is a computer.

19. The system of claim 16 wherein said inductive coupling means comprises a pair of transformers, one for inductively coupling said short duration pulse from said first output of said means for receiving, and the other for inductively coupling said short duration pulse from said second output of said means for receiving.