Control Techniques Limited

Nidec Control Techniques Limited

Colin Hargis

Richard Mark Wain

Andrew Jeremy Sykes

An electromechanical system includes an inverter drive, a component arranged during operation to generate a variable force having one or more periodic frequency components, and processing circuitry arranged to determine the power output of the inverter drive, measure a difference between the power output and a reference power output, and control an output frequency of the inverter drive as a function of the measured difference, so as to stabilise the power output during operation of the component. Other example electromechanical systems, inverter drives and methods are also disclosed.

Inverter drives having a controlled power output

According to a first aspect of the disclosure, there is provided a method of controlling a power output of an inverter. The method comprises measuring an output current of the inverter, determining a difference between the output current and a reference current, and controlling a reference input voltage of the inverter as a function of the determined difference. In a second aspect of the disclosure, there is described a system for controlling a power output of an inverter. The system comprises an inverter arranged to output a current as a function of a reference input voltage. The system further comprises a controller arranged to determine a difference between the output current and a reference current. The controller is further arranged to control the reference input voltage as a function of the determined difference. The method may allow for control of a photovoltaic inverter at a power less than its maximum capability for a given solar irradiation, which may avoid the problem of the photovoltaic array voltage rising above a level where the inverter can run.

Method and system for controlling a power output of an inverter

An electromechanical system includes an inverter drive, a component arranged during operation to generate a variable force having one or more periodic frequency components, and processing circuitry arranged to determine the power output of the inverter drive, measure a difference between the power output and a reference power output, and control an output frequency of the inverter drive as a function of the measured difference, so as to stabilize the power output during operation of the component. Other example electromechanical systems, inverter drives and methods are also disclosed.

A method of controlling a current flowing through a component of a drive comprising the steps of: estimating the current flowing through a component; estimating the temperature of the component; comparing the estimated temperature with a desired maximum temperature for the component; and adjusting the current flowing through the component based on the result of the comparing step.

Method of optimising input components

Apparatus for preventing output of an input signal is disclosed. The apparatus comprises a signal control unit comprising a signal buffering unit having an input and an output, the signal buffering unit arranged to receive an input signal and pass the input signal to the output when the signal buffering unit is powered, wherein a negative power supply terminal of the signal buffering unit is arranged to be supplied by a first power source having a voltage. The signal control unit also comprises a boost circuit arranged to boost the voltage of the first power source to a boosted voltage higher than the voltage of the first power source and supply either the voltage of the first power source or the boosted voltage to a positive power supply terminal of the signal buffering unit. The signal buffering unit is powered when the boosted voltage is supplied to the positive power supply terminal of the signal buffering unit and the signal buffering unit is not powered when voltage of the first power supply terminal is supplied to the positive power supply terminal of the signal buffering unit. Also disclosed is an apparatus for providing output voltages for driving a motor as well as a motor drive system.

Fail safe circuit

Circuits arranged to produce first and second outputs produced by first and second switch-mode converters, respectively, wherein each switch-mode converter comprises a converter input, a converter output, a converter controller, a converter controller enable input arranged to provide power to the controller, and a semiconductor power switching device coupled between the converter input and the converter controller. A first output of the first converter and a second output of the second converter are each arranged to produce a voltage of higher magnitude than the voltage at the respective converter controller enable input and converter input when the converter controller is enabled. Methods of controlling first and second outputs from first and second switch-mode converters are also disclosed.

Fail-safe interface

A drive system for an electrical load such as an electric motor or generator comprises a PWM converter and a controller therefore. A signal indicative of a condition of the converter outpost is used in a controller to drive an optimal value of PWM switching frequency based on a load characteristic that is used to control the pulse switching frequency. The system takes account of the overall system in deriving an efficient PWM switching frequency.

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Oswestry, United Kingdom

Colin Hargis