# US 7,746,024 B2 · Electric engine start system with active rectifier

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- Number: US 7,746,024 B2
- Document ID: US7746024B2
- Status: Granted
- Kind: B2
- Application number: 11/369,676
- Filed: 2006-03-07
- Published: 2007-09-20
- Granted: 2010-06-29
- Earliest claimed: 2006-03-07
- Assignees: Hamilton Sundstrand Corporation
- Inventors: Gregory I. Rozman; Thomas A. Duclos
- Web page: https://patentgrep.com/patent/US7746024B2

## CPC

- H02M 1/12: Arrangements for reducing harmonics from AC input or output
- H02M 1/15: using active elements
- H02M 5/4585: {having a rectifier with controlled elements}
- H02P 9/30: using semiconductor devices
- H02P 21/06: Rotor flux based control involving the use of rotor position or rotor speed sensors
- H02P 2101/30: for aircraft
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## Abstract

A power converter includes a PWM active rectifier and controller that minimize harmonic ripple currents on the DC link during an engine start mode (first stage) in which power is provided to an AC starter motor. The PWM active rectifier and controller also minimize harmonic currents on AC input lines during a second stage (active filter mode). The power converter also includes a PWM inverter and corresponding inverter controller that controls the performance of the AC starter motor during the first stage based on mode selection input received. The power converter system further includes pre-charge circuitry that charges a DC link capacitor located within the power converter system to a desired level prior to providing the power converter system with AC power.

## Claims

### Claim 1

An electric engine start system comprising:
alternating current (AC) input lines for carrying AC power;
a capacitor connected to each AC input line for measuring current and voltage on that AC input line;
a pulse width modulation (PWM) rectifier connected to the AC input lines;
a direct current (DC) link capacitor connected to the PWM rectifier;
a PWM inverter connected to the DC link capacitor for converting DC power provided by the PWM rectifier to AC power provided to an AC motor;
a PWM rectifier controller that controls the PWM rectifier to minimize harmonics at the DC link capacitor in a first mode in which power is provided to the AC motor, and controls the PWM rectifier to minimize harmonics on the AC input lines in a second non-motoring mode based on present voltage and current values measured on each of the AC input lines.

### Claim 2 (depends on 1)

The electric engine start system of claim 1, wherein the PWM rectifier controller in the second mode controls the PWM rectifier such that sinusoidal voltages are generated across the capacitors located on each of the AC input lines.

### Claim 3 (depends on 2)

The electric engine start system of claim 2, wherein the PWM rectifier controller generates a sinusoidal reference signal based on the voltage measured on the AC input lines and compares the sinusoidal reference signal with the present voltage measured on the corresponding AC input line to determine a correction required in the AC input line that will result in a sinusoidal signal being generated across the capacitors located on each of the AC input lines.

### Claim 4 (depends on 1)

The electric engine start system of claim 1, further including:
a PWM inverter controller connected to provide PWM signals to the PWM inverter to control the performance of the AC motor, wherein the PWM inverter controller includes a mode selector that dictates an input used by the PWM inverter controller in generating the PWM signals to provide to the PWM inverter.