Microprocessor based integrated generator set controller apparatus and method

• US 5,168,208 A
• Filed: 01/09/1991
• Issued: 12/01/1992
• Est. Priority Date: 05/09/1988
• Status: Expired due to Term

• Current Assignee: Cummins PowerGen IP, Inc. (Cummins Incorporated)
• Original Assignee: ONAN Corporation (Cummins Incorporated)
• Inventors: Koenig, David J., Schultz, Mark H.
• Primary Examiner(s): Hickey, R. J.
• Application Number:
  US07/639,131
• Time in Patent Office: 692 Days
• Field of Search: 322/25, 322/27, 322/28, 322/29
• US Class Current: 322/25
• CPC Class Codes: H02P 9/04 Control effected upon non-electric prime mover and dependent upon electric output value of the generator
• CPC Class Codes: H02P 9/30 using semiconductor devices

Abstract

An electrical generator system integrated controller device utilizing PID control and capable of regulating voltage or current, and frequency simultaneously. The device utilizes a micro-controller (30.1) to monitor the engine generator set (20), then determines the appropriate signal to deliver to the electrical generator set (20) to regulate the engine throttle (21) and the generator (22) field windings. The micro-controller (30.1) also provides for real and reactive load sharing with additional generator sets (40) while also providing for an integrated circuit interrupter module (500) to open the line from the generator (22) to the load bus (42). Additionally, serial communications (34) are provided as well as displays (35), meters (37), and operator input (36). Finally, the permissive paralleling module (700) provides that the engine electrical generator set (20) will not be allowed to be connected to the load bus (42) until standards of voltage and phase have been achieved for a set period of time.

Claims

1. A generator control system for an electrical generator mechanically linked to an engine providing rotational energy to the generator, the generator having an output voltage waveform with a frequency determined by the rotational speed of the engine;

the generator control system comprising;

(a) first sensing means operatively connected to monitor the rotational speed of the engine for generating a speed signal proportional to the rotational speed of the engine at asynchronous interrupt driven intervals;

(b) second sensing means operatively connected to monitor the voltage of the generator for generating a voltage signal indicative of the voltage of the generator at first predetermined intervals;

(c) generator output control means, operatively connected to the generator and capable of receiving second control signals, for controlling the output voltage of the generator;

(d) engine speed control means, operatively connected to the engine and capable of receiving first control signals, for controlling the output rotational speed of the engine;

(e) memory means for storing in a predetermined format a representative reference voltage and a representative reference rotational speed; and

(f) data processing means operatively connected to receive said speed signal from said first sensing means and said voltage signal from said second sensing means, for simultaneously controlling the generator output voltage and frequency, said data processing means including;

(i) means for computing, at each interrupt driven interval, an appropriate first control signal in order to maintain said speed signal substantially equal to said reference rotational speed;

(ii) means for transmitting said first control signal to said engine speed control means, whereby the engine rotational speed is maintained at said reference speed;

(iii) means for computing, at each first predetermined interval, an appropriate second control signal in order to maintain the output voltage substantially equal to said reference voltage; and

(iv) means for transmitting said desired second control signal to said generator output control means, whereby the generator output voltage is maintained at said reference voltage.

2. The generator control system as recited in claim 1, wherein:

(a) said second sensing means further comprises means for monitoring the current of the generator and for generating a current signal indicative of the current of the generator at second predetermined intervals;

(b) said generator output control means are further capable of receiving third control signals;

(c) said memory means further stores in a predetermined format a first threshold current; and

(d) said data processing means is operatively connected to receive said current signal from said second sensing means, and said data processing means further including;

(i) means for computing, at each second predetermined interval, an appropriate third control signal in order to maintain the current signal at or below said first threshold current, whereby said third control signal is a current regulating output voltage signal;

(ii) means for transmitting said third control signal to said generator output control means, whereby the generator output current is maintained below said first threshold current; and

(iii) means for selectively controlling the voltage or current of the generator wherein said data processing means selectively enable either said means for transmitting said second or third control signal in response to the magnitude of the current signal, whereby either said second or third control signal is received by said generator output control means.

3. The generator control system in accordance with claim 2, wherein said data processing means selectively controls the voltage and current of the generator in real time.

4. The generator control system in accordance with claim 3, wherein:

(a) said memory means further stores in a predetermined format a second threshold current;

(b) said data processing means switches from controlling the generator voltage to the current when the magnitude of the current signal exceeds said first threshold current; and

(c) said data processing means switches from controlling the generator current to the voltage when the magnitude of the current signal is less than said second threshold current, whereby hysteresis is added to said data processing means.

5. A generator control system for an electrical generator mechanically linked to an engine providing rotational energy to the generator, the generator having an output voltage waveform with a frequency determined by the rotational speed of the engine;

the generator control system comprising;

(a) first sensing means operatively connected to monitor the rotational speed of the engine for generating a speed signal proportional to the rotational speed of the engine at first predetermined intervals;

(b) second sensing means operatively connected to;

(i) monitor the voltage of the generator for generating a voltage signal indicative of the voltage of the generator at second predetermined intervals; and

(ii) monitor the current of the generator for generating a current signal indicative of the current of the generator at third predetermined intervals;

(c) generator output control means, operatively connected to the generator and capable of receiving first control signals, for controlling the output voltage of the generator;

(d) engine speed control means, operatively connected to the engine and capable of receiving second control signals, for controlling the output rotational speed of the engine;

(e) memory means for storing in a predetermined format a representative reference voltage, a representative reference rotational speed, a first threshold current and a second threshold current; and

(f) data processing means operatively connected to receive said speed signal from said first sensing means and said voltage and current signals from said second sensing means, for simultaneously controlling the generator output voltage and frequency, said data processing means including;

(i) means for computing, at each first predetermined interval, an appropriate desired speed signal in order to maintain said speed signal substantially equal to said reference rotational speed;

(ii) means for transmitting said desired speed signal to said engine speed control means, whereby the engine rotational speed is maintained at said reference speed;

(iii) means for computing, at each second predetermined interval, an appropriate desired voltage regulating output voltage signal in order to maintain the output voltage substantially equal to said reference voltage;

(iv) means for transmitting said desired voltage regulating output voltage signal to said generator output control means, whereby the generator output voltage is maintained at said reference voltage;

(v) means for computing, at each second predetermined interval, an appropriate desired current regulating output voltage signal in order to maintain the output current below said first threshold current;

(vi) means for transmitting said desired current regulating output voltage signal to said generator output control means, whereby the generator output current is maintained below said first threshold current; and

(vii) means for selectively controlling the voltage or current of the generator in real time, with hysteresis, by;

(A) initially enabling only said means for transmitting said desired voltage regulating output voltage signal;

(B) selectively enabling only said means for transmitting said desired current regulating output voltage signal when the magnitude of the current output signal exceeds said first threshold current; and

(C) selectively enabling only said means for transmitting said desired voltage regulating output voltage signal when the magnitude of the current output signal fails to exceed said second threshold current.