Power transducer
First Claim
1. A power transducer which outputs alternating current (AC) power having a variable voltage and a variable frequency, the power transducer comprising:
- a converter for rectifying an AC voltage of an AC power supply to convert it to a direct current (DC) voltage;
a DC intermediate circuit having a smoothing capacitor for smoothing the DC voltage of the converter;
a detecting circuit for detecting a voltage of the DC intermediate circuit;
a regenerative braking circuit disposed in the DC intermediate circuit;
a drive circuit for driving the regenerative braking circuit when the detecting circuit detects a specified voltage;
a timer for accumulating an operating time of the regenerative braking circuit to obtain a cumulative operating time;
an inverter for converting the DC voltage of the converter to an AC voltage; and
a display unit for displaying a permissible duty factor of a power semiconductor calculated or read from a nonvolatile memory,wherein a permissible duty factor and a resistance value of a regenerative braking resistor connected to the regenerative braking circuit of the DC intermediate circuit are individually set,wherein the power transducer performs the steps of;
calculating a value of current which flows in the power semiconductor, which is a switching element, in the regenerative braking circuit from the resistance value set for the regenerative braking resistor;
obtaining a generation loss of the power semiconductor from the calculated current value, andcalculating a permissible duty factor of the power semiconductor; and
determining that the regenerative braking circuit can continuously operate when both the set permissible duty factor of a regenerative braking resistor and the calculated permissible duty factor of the power semiconductor are 100% or more.
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Accused Products
Abstract
The performance of a power transducer is improved while efficiently using a power semiconductor also by managing the permissible duty factor of the power semiconductor in the regenerative braking circuit provided in the power transducer. The user is allowed to set, through an operation panel provided on the power transducer, the resistance value of the regenerative braking resistor for thermally consuming the rotational energy generated during motor deceleration. The power transducer performs the steps of: calculating the current which flows in the regenerative braking circuit from the resistance value setting; obtaining the generation loss of the power semiconductor in the regenerative braking circuit with the calculated current value; and determining the permissible duty factor of the power semiconductor from the obtained generation loss.
10 Citations
10 Claims
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1. A power transducer which outputs alternating current (AC) power having a variable voltage and a variable frequency, the power transducer comprising:
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a converter for rectifying an AC voltage of an AC power supply to convert it to a direct current (DC) voltage; a DC intermediate circuit having a smoothing capacitor for smoothing the DC voltage of the converter; a detecting circuit for detecting a voltage of the DC intermediate circuit; a regenerative braking circuit disposed in the DC intermediate circuit; a drive circuit for driving the regenerative braking circuit when the detecting circuit detects a specified voltage; a timer for accumulating an operating time of the regenerative braking circuit to obtain a cumulative operating time; an inverter for converting the DC voltage of the converter to an AC voltage; and a display unit for displaying a permissible duty factor of a power semiconductor calculated or read from a nonvolatile memory, wherein a permissible duty factor and a resistance value of a regenerative braking resistor connected to the regenerative braking circuit of the DC intermediate circuit are individually set, wherein the power transducer performs the steps of; calculating a value of current which flows in the power semiconductor, which is a switching element, in the regenerative braking circuit from the resistance value set for the regenerative braking resistor; obtaining a generation loss of the power semiconductor from the calculated current value, and calculating a permissible duty factor of the power semiconductor; and determining that the regenerative braking circuit can continuously operate when both the set permissible duty factor of a regenerative braking resistor and the calculated permissible duty factor of the power semiconductor are 100% or more. - View Dependent Claims (2, 3, 4, 5)
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6. A power transducer which outputs alternating current (AC) power having a variable voltage and a variable frequency, the power transducer comprising:
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a converter for rectifying an AC voltage of an AC power supply to convert it to a direct current (DC) voltage; a DC intermediate circuit having a smoothing capacitor for smoothing a DC voltage of the converter; a detecting circuit for detecting a voltage of the DC intermediate circuit; a regenerative braking circuit disposed in the DC intermediate circuit; a drive circuit for driving the regenerative braking circuit when the detecting circuit detects a specified voltage; a timer for accumulating an operating time of the regenerative braking circuit to obtain a cumulative operating time; and an inverter for converting the DC voltage of the converter to an AC voltage, a nonvolatile memory for pre-storing correlation data between a generation loss of a power semiconductor in the regenerative braking circuit and a permissible duty factor of the power semiconductor from a resistance value set for the regenerative braking resistor connected to the regenerative braking circuit; and a display unit for displaying a permissible duty factor of a power semiconductor calculated or read from the nonvolatile memory, wherein a permissible duty factor and the resistance value of the regenerative braking resistor are individually set, wherein the power transducer reads from the nonvolatile memory permissible duty factor data of the power semiconductor corresponding to the resistance value set for the regenerative braking resistor, and wherein, if both the set permissible duty factor of a regenerative braking resistor and the stored permissible duty factor of the power semiconductor are 100% or more, it is determined that the regenerative braking circuit can continuously operate. - View Dependent Claims (7, 8, 9, 10)
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Specification