# US 7,743,616 B2 · Control system for a generator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,743,616 B2 - Document ID: US7743616B2 - Status: Granted - Kind: B2 - Application number: 11/548,867 - Filed: 2006-10-12 - Published: 2008-04-17 - Granted: 2010-06-29 - Earliest claimed: 2006-10-12 - Assignees: Thermo King Corporation - Inventors: David J. Renken; Bernard Wayne Benson; Randy S. Burnham; Erich Lucht - Web page: https://patentgrep.com/patent/US7743616B2 ## CPC - H02P 9/04: Control effected upon non-electric prime mover and dependent upon electric output value of the generator - B60H 1/3222: {characterised by the compressor driving arrangements, e.g. clutches, transmissions or multiple drives (B60H1/3208, B60H1/3226 take precedence)} - B60H 1/3226: {Self-contained devices, i.e. including own drive motor} - B60H 1/3232: {particularly adapted for load transporting vehicles (B60H1/3226 takes precedence)} - F25B 27/00: Machines, plants or systems, using particular sources of energy (F25B30/06 takes precedence) - F25B 2327/12: using internal combustion engines - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - B60H: ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS ## Abstract A generator set for a transport refrigeration unit that is operable at a first frequency and a second frequency. The generator set includes a generator and a prime mover coupled to the generator. The prime mover selectively drives the generator in least at a first non-zero speed and a second non-zero speed. A sensor is in electrical communication with the generator to sense a load of the generator and to deliver a signal indicative of the generator load. A controller is in electrical communication with the generator, the prime mover, and the sensor, and receives the signal indicative of the generator load. The controller selectively operates the generator at one of the first speed and the second speed in response to the signal indicative of the generator load. ## Claims ### Claim 1 A generator set for a transport refrigeration unit that is operable at a first frequency and a second frequency, the generator set providing electrical power to the transport refrigeration unit, the generator set comprising: a housing; a generator disposed in the housing; a prime mover disposed in the housing and coupled to the generator to selectively drive the generator in least at a first non-zero speed and a second non-zero speed; a sensor in electrical communication with the generator to sense a load of the generator and to deliver a signal indicative of the generator load; and a controller in electrical communication with the generator, the prime mover, and the sensor, the controller configured to receive the signal indicative of the generator load, and configured to selectively operate the generator at one of the first non-zero speed and the second non-zero speed in response to the signal indicative of the generator load. ### Claim 2 (depends on 1) The generator set of claim 1, wherein the generator is defined by a load capacity, and wherein the generator load defines a load ratio with respect to the load capacity. ### Claim 3 (depends on 2) The generator set of claim 2, wherein the controller is configured to operate the generator at the first speed in response to the generator load above a predetermined load ratio, and wherein the controller is configured to operate the generator at the second speed in response to the generator load below the predetermined load ratio. ### Claim 4 (depends on 2) The generator set of claim 2, wherein the controller is configured to operate the generator at the second speed in response to the generator load below a first predetermined load ratio, and wherein the controller is configured to operate the generator at the first speed in response to the generator load above a second predetermined load ratio. ### Claim 5 (depends on 4) The generator set of claim 4, wherein the second predetermined load ratio is different from the first predetermined load ratio. ### Claim 6 (depends on 4) The generator set of claim 4, wherein the first predetermined load ratio is at about 50 percent of the generator load capacity, and wherein the second predetermined load ratio is at about 75 percent of the generator load capacity. ### Claim 7 (depends on 1) The generator set of claim 1, wherein the controller is configured to maintain the generator at the first speed for a minimum predetermined time in response to startup of the prime mover. ### Claim 8 (depends on 1) The generator set of claim 1, wherein the controller is configured to maintain the generator at the second speed for a minimum predetermined time after the generator is varied from the first speed to the second speed. ### Claim 9 (depends on 1) The generator set of claim 1, wherein the generator is operable at a first frequency in response to the generator being driven at the first speed, and operable at a second frequency in response to the generator being driven at the second speed. ### Claim 10 (depends on 9) The generator set of claim 9, wherein the first frequency and the second frequency are determined by at least one of a prime mover speed and a field voltage of the generator. ### Claim 11 (depends on 9) The generator set of claim 9, wherein the first frequency of the generator is approximately equal to the first frequency of the transport refrigeration unit, and wherein the second frequency of the generator is approximately equal to the second frequency of the transport refrigeration unit. ### Claim 12 (depends on 11) The generator set of claim 11, wherein the first frequency of the generator is 60 Hertz and the second frequency of the generator is 50 Hertz. ### Claim 13 (depends on 9) The generator set of claim 9, wherein the controller is configured to operate the generator at a first output voltage in response to the generator being operated at the first frequency, and wherein the controller is configured to operate the generator at a second output voltage in response to the generator being operated at the second frequency. ### Claim 14 (depends on 13) The generator set of claim 13, wherein the first output voltage is at about 460 volts, and wherein the second output voltage is at about 380 volts. ### Claim 15 (depends on 1) The generator set of claim 1, wherein the first speed is at about 1800 revolutions per minute, and wherein the second speed is at about 1500 revolutions per minute. ### Claim 16 (depends on 1) The generator set of claim 1, further comprising an electro-mechanical device coupled to the prime mover, wherein the controller is in electrical communication with the electro-mechanical device to selectively drive the generator at the first speed and the second speed. ### Claim 17 (depends on 1) The generator set of claim 1, wherein the signal indicative of the generator load is determined by at least one of a field current of the generator, a field voltage of the generator, and an output current of the generator. ### Claim 18 A method of controlling a generator set for a transport refrigeration unit operable at a first frequency and a second frequency, the method comprising: providing a generator and a prime mover coupled to the generator; driving the generator with the prime mover in least at one of a first non-zero speed and a second non-zero speed; sensing a load of the generator using a sensor and delivering a signal indicative of the sensed generator load to a controller in electrical communication with the prime mover and the generator; and selectively varying the speed of the generator between the first speed and the second speed with the controller in response to the sensed generator load. ### Claim 19 (depends on 18) The method of claim 18, further comprising starting the prime mover; and driving the generator with the prime mover at the first speed for a minimum predetermined time. ### Claim 20 (depends on 18) The method of claim 18, wherein selectively varying the speed of the generator includes defining a load capacity of the generator; defining a generator load ratio based on the sensed generator load and the load capacity of the generator; and driving the generator with the prime mover at one of the first speed and the second speed. ### Claim 21 (depends on 20) The method of claim 20, wherein driving the generator at one of the first speed and the second speed includes driving the generator with the prime mover at the first speed; changing the generator speed from the first speed to the second speed in response to the sensed generator load indicative of the generator load ratio below a predetermined load ratio; and driving the generator with the prime mover at the second speed. ### Claim 22 (depends on 21) The method of claim 21, wherein driving the generator with the prime mover at the second speed includes driving the generator at the second speed for a minimum predetermined time. ### Claim 23 (depends on 20) The method of claim 20, wherein driving the generator at one of the first speed and the second speed includes driving the generator with the prime mover at the second speed; changing the generator speed from the second speed to the first speed in response to the sensed generator load indicative of the generator load ratio above a predetermined load ratio; and driving the generator with the prime mover at the first speed. ### Claim 24 (depends on 20) The method of claim 20, wherein selectively varying the speed of the generator includes varying the speed of the generator from the first speed to the second speed in response to the sensed generator load indicative of the generator load ratio below a first predetermined load ratio; and varying the speed of the generator from the second speed to the first speed in response to the sensed generator load indicative of the generator load ratio above a second predetermined load ratio. ### Claim 25 (depends on 24) The method of claim 24, wherein varying the speed of the generator from the first speed to the second speed includes decreasing the generator speed in response to the generator load indicative of the generator load ratio below the first predetermined load ratio. ### Claim 26 (depends on 24) The method of claim 24, wherein varying the speed of the generator from the second speed to the first speed includes increasing the generator speed in response to the generator load indicative of the generator load ratio above the second predetermined load ratio. ### Claim 27 (depends on 18) The method of claim 18, further comprising operating the generator at a first frequency in response to driving the generator at the first speed; and operating the generator at a second frequency in response to driving the generator at the second speed. ### Claim 28 (depends on 18) The method of claim 18, wherein selectively varying the generator speed includes varying the generator between a first frequency and a second frequency in response to varying the generator speed; and varying an output voltage of the generator in response to varying the generator between the first frequency and the second frequency. ### Claim 29 (depends on 28) The method of claim 28, wherein varying the generator between the first frequency and the second frequency includes determining the frequency with the controller by sensing at least one of a prime mover speed and a magnetic field voltage of the generator. ### Claim 30 (depends on 18) The method of claim 18, wherein sensing the generator load includes sensing at least one of a field current of the generator, a field voltage of the generator, and an output current of the generator. ### Claim 31 A generator set for a transport refrigeration unit, the transportation refrigeration unit operable at a first frequency and a second frequency, the generator set providing electrical power to the transport refrigeration unit, the generator set comprising: a housing; a generator disposed in the housing and configured to provide electrical power to the transportation refrigeration unit; a prime mover disposed in the housing and coupled to the generator to selectively drive the generator at least at a first non-zero speed and a second non-zero speed; a controller in electrical communication with the generator and the prime mover; and a timer in electrical communication with the controller, the timer operable to determine a duration of time that the prime mover drives the generator at the first non-zero speed, wherein the controller is operable to change the prime mover from operating the generator at the first non-zero speed to operating the generator at the second non-zero speed based on the duration of time determined by the timer. ### Claim 32 (depends on 31) The generator set of claim 31, wherein the prime mover is a diesel engine. ### Claim 33 (depends on 31) The generator set of claim 31, wherein the controller is configured to maintain the generator at the first non-zero speed for a minimum predetermined time in response to startup of the prime mover. ### Claim 34 (depends on 31) The generator set of claim 31, wherein the generator is operable at a first frequency in response to the generator being driven at the first non-zero speed, and operable at a second frequency in response to the generator being driven at the second non-zero speed. ### Claim 35 (depends on 34) The generator set of claim 34, wherein the first frequency and the second frequency are determined by at least one of a prime mover speed and a field voltage of the generator. ### Claim 36 (depends on 34) The generator set of claim 34, wherein the first frequency of the generator is approximately equal to the first frequency of the transport refrigeration unit, and wherein the second frequency of the generator is approximately equal to the second frequency of the transport refrigeration unit. ### Claim 37 (depends on 36) The generator set of claim 36, wherein the first frequency of the generator is 60 Hertz and the second frequency of the generator is 50 Hertz. ### Claim 38 (depends on 34) The generator set of claim 34, wherein the controller is configured to operate the generator at a first output voltage in response to the generator being operated at the first frequency, and wherein the controller is configured to operate the generator at a second output voltage in response to the generator being operated at the second frequency. ### Claim 39 (depends on 38) The generator set of claim 38, wherein the first output voltage is at about 460 volts, and wherein the second output voltage is at about 380 volts. ### Claim 40 (depends on 31) The generator set of claim 31, wherein the first non-zero speed is about 1800 revolutions per minute, and wherein the second non-zero speed is about 1500 revolutions per minute. ### Claim 41 (depends on 31) The generator set of claim 31, further comprising an electro-mechanical device coupled to the prime mover, wherein the controller is in electrical communication with the electro-mechanical device to selectively drive the generator at the first non-zero speed and the second non-zero speed. ### Claim 42 (depends on 31) The generator set of claim 31, wherein the controller is operable to change the prime mover from operating the generator at the first non-zero speed to operating the generator at the second non-zero speed in response to the duration of time determined by the timer being in excess of a predetermined time.