CONTROLLER FOR CONTROLLING A POWER CONVERTER

• US 20170201180A1
• Filed: 03/28/2017
• Published: 07/13/2017
• Est. Priority Date: 03/26/2010
• Status: Active Grant

• Current Assignee: Redisem Ltd.
• Original Assignee: Russell Jacques
• Inventors: JACQUES, Russell, VAN DER DUIJIN SCHOUTEN, Nicolaas, COULSON, David
• Granted Patent: US 10,396,669 B2
• Time in Patent Office: Days
• CPC Class Codes: H01F 38/20 Instruments transformers
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/083 for the ignition at the zero crossing of the voltage or the current
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33571 Half-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 3/338 in a self-oscillating arrangement H02M3/337 takes precedence
• CPC Class Codes: H02M 3/3385 with automatic control of output voltage or current H02M3/33561 takes precedence
• CPC Class Codes: H02M 7/5383 in a self-oscillating arrangement H02M7/538 takes precedence
• CPC Class Codes: H03K 17/13 Modifications for switching at zero crossing generating an impulse at zero crossing H03K5/1536
• CPC Class Codes: H03K 17/133 in field-effect transistor switches
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A power converter controller and methods for its operation are provided that can control a self-oscillating power converter that uses a Bipolar Junction Transistor (BJT) as a switch by manipulating the current flowing in a control winding. The controller is able to determine the optimum time to remove a short circuit applied to the control winding, as well as being able to determine the optimum time to pass current through the control winding. The controller can further draw power from the power converter using the control winding. The controller is capable of maintaining the midpoint voltage of the power converter in the case that the converter has more than one switch. The controller estimates the output power of the converter without requiring a connection to the secondary side of the converter transformer. The controller further controls entry and exit into a low-power mode in which converter oscillations are suppressed.

Claims

1. A method of controlling a power converter having a transformer, the transformer having a primary input winding and a secondary output winding, the method comprising:

measuring the average rectified alternating current through a resistor coupled in series with the primary input winding;

comparing the average rectified current to a reference level; and

controlling the switching of the power converter based on the difference between the average current and the reference level.

2. A method according to claim 1, wherein said measuring step includes:

measuring the full-wave rectified voltage across said resistor; and

averaging said rectified voltage with a filter.

3. A method according to claim 1, wherein:

the comparing step includes integrating the difference between the average alternating current and a reference level; and

the difference based on which the power converter is controlled is the integrated difference between the average current and said reference level.

4. A method according to claim 2, wherein:

the comparing step includes integrating the difference between the average alternating current and a reference level; and

the difference based on which the power converter is controlled is the integrated difference between the average current and said reference level.

5. A controller for a switched power converter having a transformer and a switch, the transformer having a primary input winding and a secondary output winding, comprising:

first and second current sensing resistor connections for connection to a current sensing resistor coupled in series with the primary input winding;

a measurer for determining the average rectified alternating current flowing through said current sensing resistor;

a comparator for comparing the determined average rectified current to a reference level;

wherein

the controller controls the switching of the switch based on the output of the comparator.

6. A controller according to claim 5, wherein the measurer comprises:

a rectifier coupled to the first and second current sensing resistor connections for rectifying the voltage across said current sensing resistor induced by the switched current flowing through it; and

a low pass filter for filtering the rectified voltage.