Abstract:
A circuit for providing power factor correction includes a boost converter circuit with a boost inductance and a power factor correction switch and a control circuit. The control circuit provides a pulse width modulated signal to control the on time of a PFC switch, and also includes a power factor correction pulse width modulated device receiving as inputs a rectified AC input voltage, a DC bus voltage, a signal proportional to the current through the inductor and a reference current signal. The power factor correction pulse width modulated device also includes a pulse width modulated generator operable to provide the pulse width modulated signal to control the on time of the PFC circuit and a pulse width modulated blanking device operable to provide an enable/disable signal to disable the pulse width modulated generator when predetermined conditions are met.
Abstract:
A circuit for providing power factor correction comprising a boost converter circuit having a boost inductance and a power factor correction switch coupled in series with the boost inductance, the boost inductance and power factor correction switch being coupled across the output of a rectifier being supplied with AC power from an AC line, the boost converter circuit further comprising a boost diode coupled to a junction between the inductor and the switch, an output of the boost diode coupled to an output capacitor, a DC bus voltage being provided across the output capacitor, further comprising a control circuit receiving as inputs a rectified AC input voltage from the rectifier, a signal proportional to current through the inductor and the DC bus voltage across the capacitor, and wherein the control circuit provides a pulse width modulated signal to control the on time of the PFC switch, further comprising an enable/disable circuit receiving as inputs the rectified AC input voltage and the DC bus voltage, the circuit instantaneously comparing the rectified AC input voltage and the DC bus voltage and controlling the control circuit whereby the control circuit provides the pulse width modulated signal to control the PFC switch when the rectified AC input voltage is less than the DC bus voltage and disables the generation of the pulse width modulated signal to the PFC switch when the rectified AC input voltage is greater than DC bus voltage.
Abstract:
An active EMI filter having a rectifier coupled to an AC network, the rectifier supplying DC power to a DC bus, and the DC bus feeding an inverter stage for providing AC power to a load. The load having a ground return line (GND) to a ground connection of the AC network. The active filter having a transistor switching stage (Q1, Q2) coupled across the DC bus. A current sensor (G1, G2) coupled to the DC bus for sensing the common mode current flowing in the DC bus, and the current sensor (G1, G2) having inputs coupled to respective legs of the DC bus and an output driving the transistor switching stage (Q1, Q2). A capacitor coupling the transistor switching stage (Q1, Q2) and the ground return line (GND). The capacitor providing a cancellation current to the ground return line (GND) from the transistor switching stage (Q1, Q2) to substantially cancel the common mode current in the ground return line (GND).
Abstract:
A circuit for protecting against controller failure wherein the controller provides control signals for controlling a DC to AC inverter fed by a DC bus and driving a permanent magnet motor, the circuit comprising a first circuit for monitoring the DC bus voltage and, in the event the DC bus voltage exceeds a first threshold due to a counter EMF generated by the motor, for producing a signal to the controller to provide a switch state to the inverter whereby the counter EMF is dissipated substantially in a motor circuit resistance of the permanent magnet motor as a result of a short circuit condition provided by the switch state of the inverter, thereby preventing the DC bus voltage of the inverter from exceeding the first threshold and causing the permanent magnet motor speed to be reduced.
Abstract:
A power inverter control adjusts input power to track with output power to reduce energy handling requirements for an inverter DC bus. Input power to the power inverter circuit is measured and compared with a measurement of inverter output power. The comparison result is applied to a power factor correction circuit to adjust input power to track with output power, while obtaining a good power factor for the power inverter circuit. The energy requirements and ripple voltages or ripple currents on the DC bus are reduced, leading to a reduction in rating specifications for passive energy storage elements on the DC bus.
Abstract:
Apparatus for reconstructing the phase currents of a multiphase load driven by a multiphase inverter fed by a DC link and controlled by a PWM controller, the apparatus including a sensor in the DC link, first and second sampling arrangements for sampling the current in the DC link by obtaining an output from said sensor, the first sampling arrangement obtaining a first sample of the current in the DC link during a first time period corresponding to a first switching pattern of said multiphase inverter and storing said first sample; the second sampling arrangement obtaining a second sample of the current in the DC link during a second time period after said first time period and corresponding to a second switching pattern of said multiphase inverter and storing said second sample; an A/D converter for converting said first sample to a digital signal during a time period after said first time period and for converting said second sample to a digital signal during a following third time period.
Abstract translation:用于重建由DC链路馈送并由PWM控制器馈送并由PWM控制器馈送的多相逆变器驱动的多相负载的相电流的装置,该装置包括在DC链路中的传感器,用于对DC链路中的电流进行采样的第一和第二采样装置 通过从所述传感器获得输出,第一采样装置在对应于所述多相逆变器的第一切换模式的第一时间段期间获得DC链路中的电流的第一采样并存储所述第一采样; 所述第二采样装置在所述第一时间段之后的第二时间段期间获得DC链路中的电流的第二采样,并且对应于所述多相逆变器的第二开关模式并存储所述第二采样; A / D转换器,用于在所述第一时间段之后的时间段期间将所述第一样本转换为数字信号,并在随后的第三时间段期间将所述第二样本转换为数字信号。
Abstract:
A power factor correction circuit for driving a switch of a boost type converter circuit having an AC line frequency input, comprising a sense circuit for sensing and comparing the output voltage of the boost type converter circuit to a reference voltage, a circuit responsive to the output of the sense circuit for providing a drive signal for driving the switch, wherein the drive signal comprises a pulsed signal comprising a pulse grouping during each half cycle of the AC line frequency comprising at least one pulse wherein the number of pulses and frequency of the pulses of the pulse grouping changes with the output of the sense circuit up to a threshold value with the pulse width of the pulses being substantially constant; and when the output of the sense circuit has reached the threshold value, the pulse width of the pulses of the pulse grouping are varied in accordance with the output of the sense circuit.
Abstract:
A multiple axis servo control implements a multi-tasking PWM control unit to provide PWM signals for multiple axes in a single unit. A time slice mechanism provides axis selection signals based on a system clock signal to permit control parameters of the selected axis to be processed to control the selected motor drive axis. The single unit PWM control mechanism eliminates complex and costly multiple axis networks typically associated with independent servo motor controls for each axis in a multi-axis system. A single PWM unit implementation also permits the reduction of components for closed loop current control and closed loop velocity control in the multi-axis servo control system.
Abstract:
An active EMI filter for reducing common mode current in a circuit comprising: a transistor switching stage (Q1, Q2) coupled across a DC bus, a current sensor (CT) coupled to the DC bus for sensing the common mode current flowing in the DC bus and proportional to the common mode current flowing in the ground return line from or to an AC load and having an output driving the transistor switching stage; a capacitor coupling said transistor switching stage and said ground return line and wherein said current sensor and said switching stage are coupled in a feed forward arrangement whereby the switching stage is coupled across said DC bus between said rectifier and said current sensor, wherein said capacitor provides a cancellation current to said ground return line from said transistor switching stage to substantially cancel the common mode current in said ground return line.
Abstract:
A motor drive system (10) control provides global closed loop feedback to cooperatively operate system components to adaptively reduce noise and provide noise cancellation feedback. An active EMI filter (12) reduces differential and common mode noise on an input and provides a noise level indication to a system controller (11). Power switches in both a power converter (14) and power inverter (16) are cooperatively controlled with dynamic dv/dt control to reduce switching noise according to a profile specified by the controller 11). The dv/dt control is provided as an analog signal to a high voltage IC and codified as a pulse width for a level shifting circuit supplying control signals to the high voltage gate drive (18). A noise extraction circuit and technique obtain fast noise sampling to permit noise cancellation and adaptive noise reduction.