EP0732798A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
PWM control apparatus and a system using same
Assignee: Hitachi Ltd
•
Filing: 1996-03-11
•
Granted: —
•
Expires: 2016-03-11
Abstract
Abstract In PWM control apparatus having a command value generator, a pulse width modulator which, in response to a command value from said command value generator, computes a pulse wave to be output having a width corresponding to said command value for period specified Δt, and a power conversion unit including semiconductor elements which are driven by said pulse wave, the improvement is characterized by further comprising: means for compensating a command value by sampling said command value at least twice in said period specified Δt to compute an average value of said command value on the basis of said sampling, whereby said pulse width modulator computes said pulse wave to be output in response to said average value of said command value from said means for compensating said command value. Further, the same PWM control apparatus comprises: a triangle wave carrier generator which generates a triangle wave carrier signal having a cycle which is n times (n is integer) said period specified Δt, wherein, said means for compensating said command value is adapted to compute an average value of said command value at every sampling thereof within a period defined by a half cycle of said triangle wave carrier signal, i.e., from a plus peak to a minus peak or vice versa, and wherein, said pulse width modulator is adapted to compare said average value with said triangle wave carrier thereby to compute said pulse wave to be output.
Inventors
- 👤 Yoshitaka Oonuma-ryo E0720 Iwaji
- 👤 Toshiaki Okuyama
- 👤 Takashi Oonuma-ryo E0518 Ikimi
- 👤 Masahiro Tobise
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 11:39
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/539; H02M7/5395; B; B21; B21B; B21B37/00; B21B37/46
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
130 words
In PWM control apparatus having a command value generator, a pulse width modulator which, in response to a command value from said command value generator, computes a pulse wave to be output having a width corresponding to said command value for period specified Δt, and a power conversion unit including semiconductor elements which are driven by said pulse wave, the improvement is characterized by further comprising: means for compensating a command value by sampling said command value at least twice in said period specified Δt to compute an average value of said command value on the basis of said sampling, whereby said pulse width modulator computes said pulse wave to be output in response to said average value of said command value from said means for compensating said command value.
Claim 2
Dependent Claim
49 words
PWM control apparatus according to claim 1, wherein said means for compensating command value is adapted to compute an average value of said command value in said period specified Δt on the basis of an amplitude and a phase of said command value output from said command value generator.
Claim 3
Dependent Claim
112 words
PWM control apparatus according to claim 1, characterized by comprising: a triangle wave carrier generator which generates a triangle wave carrier signal having a cycle which is n times (n is integer) said period specified Δt, wherein, said means for compensating said command value is adapted to compute an average value of said command value at every sampling thereof within a period defined by a half cycle of said triangle wave carrier signal, i.e., from a plus peak to a minus peak or vice versa, and wherein, said pulse width modulator is adapted to compare said average value with said triangle wave carrier thereby to compute said pulse wave to be output.
Claim 4
Dependent Claim
74 words
PWM control apparatus according to claim 2 comprising a coordinate transformation unit which in response to an amplitude and a phase of a command value from said command generator transforms same into an ac quantity command value, and wherein said command value compensating means is adapted to compute an average value of said ac quantity command value within each of said period Δt by shifting the phase of transformation in said coordinate transformation unit.
Claim 5
Dependent Claim
92 words
PWM control apparatus according to claim 4 wherein said command value compensating means is adapted to calculate a start phase and terminate phase of said command value corresponding to a start time and terminate time of each of said period Δt, execute coordinate-transformation of said command value by shifting 90 degrees relative to these two phases respectively, dividing a difference between two transformed command values by an incremental phase angle of said command value corresponding to each of said period Δt, said value obtained above being input to said pulse width modulator.
Claim 6
Dependent Claim
55 words
A motor drive system having an ac motor, an electric conversion unit for driving said ac motor, a PWM controller for controlling said electric conversion unit, and a motor controller for producing a command value to said PWM controller, wherein said PWM controller comprises either one of PWM control apparatus as claimed in claims 1-5.
Claim 7
Dependent Claim
103 words
An ac motor drive system having an inverter for outputting ac power, an ac motor to be driven by said inverter, means for estimating or sensing the number of revolutions of the ac motor, means for producing a command to influence the number of revolutions, means for producing a command to said inverter so that an estimated or sensed value of the number of revolutions coincides with said command value, and PWM control means for controlling the inverter in response to said command, wherein said PWM control means characterized by comprising either one of said PWM control apparatus as claimed in claims 1-5.
Claim 8
Dependent Claim
93 words
Rectifying apparatus having a power converter which is supplied a power from an ac power supply and converts said ac power into a dc power, means for producing a command value to control at least an input power factor of said power converter or a dc power voltage (or current) to be converted by said power converter, and PWM control means for controlling said power converter on the basis of said command value, wherein said PWM control means is characterized by comprising either one of PWM control apparatuses as claimed in claims 1-5.
Claim 9
Dependent Claim
71 words
A mill drive system having a power inverter which outputs an ac power, an ac motor which is driven by said power inverter, a mill machine which drives mill rolls with said ac motor, and PWM control means for controlling said power inverter to apply speed control to said mill rolls, wherein said PWM control means is characterized by comprising either one of PWM control apparatuses as claimed in claims 1-5.
Claim 10
Dependent Claim
56 words
An electric car or vehicle having a power inverter which outputs an ac power, an ac motor which is driven by said power inverter, and PWM control means for controlling said power inverter, wherein said PWM control means is characterized by comprising either one of said PWM control apparatuses as claimed in claims 1 to 5.
Claim 11
Dependent Claim
62 words
An elevator drive system having a power inverter which outputs an ac power, an ac motor which is driven by said power inverter, an elevator having said ac motor as its drive source, and PWM control means for controlling said power inverter, wherein said PWM control means is characterized by comprising either one of PWM control apparatuses as claimed in claims 1-5.
Claim 12
Dependent Claim
82 words
A reactor power (var) compensation apparatus connected to an electric power system, having a power converter connected to said power system for converting ac to dc, a command value generator which computes and produces a command value to said power converter so as to control a power factor of said electric power system, and a PWM controller for controlling said power converter, wherein said PWM control means is characterized by comprising either one of PWM control apparatuses as claimed in claims 1-5.
Claim 13
Dependent Claim
87 words
A variable-speed pumped storage power plant system having a pump turbine, a motor generator which is driven by said pump turbine, a power conversion unit for exciting said motor generator by ac, PWM control means for controlling said power conversion unit, and a command value generator for producing a command value to said PWM control means so as to control the number of revolutions of said motor-generator, wherein said PWM control means is characterized by comprising either one of PWM control apparatuses as claimed in claims 1-5.
Claim 14
Dependent Claim
48 words
In an ac-ac converter system which directly converts an ac power input to an ac output having an arbitrary frequency, amplitude and phase, an improved PWM cycloconverter system comprises either one of PWM control apparatuses as claimed in claims 1-5 to obtain said arbitrary frequency, amplitude and phase.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.