JP2008535460A - Boost converter with PFC circuit without bridge - Google Patents

Abstract

A boost power supply circuit for providing a DC output voltage, comprising first and second semiconductor switches coupled between respective input lines and a common connection. An AC input voltage from an AC source is provided between the input lines, the first and second diodes are coupled in series with each of the switches, and the third and fourth diodes are in parallel with each of the switches or with the switch. Coupled in a freewheeling relationship, the inductor is coupled to at least one of the input lines, and the controller controls the switch conduction time by providing a pulse width control signal to each of the switches, where the controller During the positive half cycle of the AC voltage, at least one of the switches is turned on to allow energy storage in the inductor, and at least one switch is turned off so that the energy stored in the inductor is the first and second diodes. And a load mounted through one of the third and fourth diodes To allow it to be fed.
During the negative half cycle of the AC voltage, the controller turns on at least one of the switches to allow energy storage in the inductor and turns off at least one switch so that the energy stored in the inductor is And one of the second diodes and one of the third and fourth diodes can be supplied to the mounted load. The controller determines the pulse on-time and off-time of the pulse width modulation control signal during each half cycle of the AC voltage, the on-time and off-time of the pulse being based on voltage detection or current detection, the output It is controlled to adjust the voltage and correct the power factor of the AC input voltage.
[Selection] Figure 5

Description

  This application is related to US Provisional Patent Application No. 60 / 666,950 (IR-2965 PROV) filed March 31, 2005.

  This application is based on US Provisional Patent Application No. 60/507901 filed on October 1, 2003, and is part of US Patent Application No. 10/9534444 (IR-2593) filed on September 29, 2004. It is a continuation application.

  The present invention relates to a boost converter with a bridgeless PFC circuit, and more particularly to a converter circuit that can be used, for example, in air conditioning applications.

  Increased demand for indoor air conditioners driven by environmental changes is beginning to affect summer energy consumption in all industrialized and emerging countries.

  Consumers interested in new legal regulations and more energy are demanding better energy efficient devices. However, finding a power management circuit that meets full efficiency and control criteria poses significant challenges to the designer in terms of cost, reliability, and ease of design.

  The pursuit of efficient use of power places greater demands on designers of consumer products for the home market. One element of increasing complexity is the power factor controlled input converter stage required by new regulations in Europe and China.

  Due to the seriousness of energy problems in almost all countries, the government has decided to significantly reduce waste of energy consumption by increasing the energy efficiency of appliances such as washing machines, water heaters, and especially air conditioning equipment. The target program is deployed.

  Indoor and residential air conditioning is becoming increasingly popular not only in the United States and Japan, but also in Europe and emerging countries such as China and India.

  In the United States, the Department of Energy recently promulgated various new energy efficiency standards for many conventional appliances. Similar standards have already been implemented in Europe and Japan.

  The residential air conditioning market (manufacturing about 35 million units worldwide) is in essence a “high impact product” for energy efficiency programs.

  In the United States, the latest regulations on air conditioning equipment and heat pumps provide strict minimum efficiency standards that will come into effect on January 23, 2006. By reducing the SEER (seasonal energy efficiency ratio) of the air conditioner, annual operating costs can be reduced by 50-75%.

  In the case of air conditioners, the economic power savings are more than usual because the power of the compressor is essentially higher than in other home appliance applications.

  However, these savings are hardly achievable without standard AC induction or wider adoption of variable speed compressor drives operating BLDC compressors. On the other hand, the adoption of electronic inverters to control motors has generally not been sufficient to achieve these results.

  The bridge rectifier / capacitor in these inverter circuits (and linear and switch mode power supplies) because the input bulk capacitor charges only towards the peak of the voltage sine wave and thus causes a current peak as shown in FIG. The front end exhibits a load that is very nonlinear with respect to the mains.

  Thus, this non-sinusoidal current pulse has harmonics of the fundamental power line frequency, each of which has a large energy content.

  Insufficient power factor, often increased by many similar devices operating at the same time, and these combined effects of harmonic disturbances reduce supply network capacity, further exacerbate energy problems, and stop distribution And contribute to the shortage. Therefore, this type of electronic motor control needs to employ a power factor correction circuit in the input section in order to operate efficiently within national and international standards.

  The existing standard EN / IEC 61000-3-2 has four product classes, each with its own set of limits on harmonic current and power factor.

  The EN61000-3-2 standard applies to all products up to 16 amps per phase. Existing standards classify all motor drives as class A, and these are subject to the strictest limits. Various methods have been adopted in the industry to address this problem.

  The simplest solution is passive PFC technology, according to which, for example, a simple inductor is connected directly in series with the power line. In the case of indoor air conditioning unit power levels, this simple solution limitation is too many, ie, unsatisfactory in inductor size and weight, cost, and power factor correction.

  To improve performance, the only practical option is to employ active PFC technology. However, active PFC circuits are more complex and require more components. These components, if not properly selected, affect the overall efficiency of the device.

  The topology of FIG. 4 is typically used as a preregulator for converters operating with general purpose AC power input. A converter is a power source, motor driver, or other power electronics that need to comply with power line quality standards.

  It uses an off-line bridge rectifier followed by a series inductor L and a shunt switch M. The stored inductive energy is discharged to the storage capacitor C to form a regulated low ripple voltage DC output. This circuit accommodates power levels up to about 2.5 KW.

  It is clear from FIG. 4 that the power flow from the AC input to the DC load includes two diode voltage drops in the rectifier and one diode voltage drop in the boost diode DB. In addition, there is a voltage drop associated with the current sensing resistor R.

  This increased complexity in power management circuit design presents additional challenges to engineers and manufacturers.

  Advances in semiconductor manufacturing and packaging technology are available for power in the appliance and optoelectronic markets, helping to solve these new problems.

  The trend in inverter applications to integrate all power semiconductors in a single power package can easily be extended to input converters, addressing and making use of power management solutions.

  New solutions to address these issues have been developed using bridgeless configurations. This provides a high-performance input converter, for example for compressor drives and motor-controlled drives, which uses a new topology and is uniquely developed by International Rectifier Corporation. Packaging techniques can be used.

  Of the various power factor circuit topologies, the bridgeless topology disclosed in 10/953444 (IR-2593) is particularly relevant for motor control applications, specifically for compressor drives in air conditioners. It is effective for some reason.

  With reference to FIGS. 2 and 3, the operation of the basic topology will be described in terms of two states of input voltage from the mains power supply.

When the positive half-cycle AC input voltage goes positive, the gate of MOSFET M1 is driven high and current IL flows from the input through the inductor to store energy. When M1 is turned off, current flows through D1, through the load, and through the diode body of MOSFET M2, returning to the input mains, the inductor energy is released.

  During the off time, the current through the inductor L (which discharges its energy during this period) flows through the boost diode D1, and the circuit is closed through the load.

Negative Half Cycle During the negative half cycle, M2 is turned on and current flows through inductor L, storing energy. When M2 is turned off, current flows through D2, through the load, and energy is released as it returns to the main line through the diode body of M1.

  Note that the two MOSFETs are driven simultaneously by the presence of a diode body that recirculates current during opposite polarity cycles.

  As a result of new silicon technologies, as well as advanced integration and packaging technology innovations, this input converter topology is easily implemented.

  Compared to conventional single-switch boost topology PFC circuits, the bridgeless topology provides increased efficiency and reduced cost. That is,

There is one less diode in efficiency improvement and power flow.
· IGBT diode connected to both ends of conducting at a frequency of mains, since it has a smaller V _F, they do not require high-speed recovery.
-The efficiency of IGBT is good.

Cost reduction and input AC rectifiers are not separated.
・ There is a possibility to reduce the input filter.
• The heat sink becomes smaller due to the distribution of heat sources and better efficiency.
• The die size (half current per switch) of the two IGBTs is smaller.
Gate drive requirements are reduced due to the smaller active portion of the smaller IGBT die.

  In view of these considerations, various embodiments of the present invention provide boosted power supplies that provide a DC output voltage with first and second semiconductor switches coupled between respective input lines and a common connection. Providing a circuit, an AC input voltage from an AC source is provided between the input lines, a first and second diode coupled in series with each of the switches, and a third and fourth diode in parallel with each of the switches. And / or coupled in a switch and freewheel relationship, the inductor is coupled to at least one of the input lines, and the controller controls the switch conduction time by providing a pulse width control signal to each of the switches; There, the controller turns on at least one of the switches during the positive half-cycle of the AC voltage to turn on the energy in the inductor. Enabling storage and turning off at least one switch so that the energy stored in the inductor is applied to a load attached through one of the first and second diodes and one of the third and fourth diodes. And the controller turns on at least one of the switches to allow energy storage in the inductor and turns off at least one switch during the negative half cycle of the AC voltage. Allows the stored energy to be supplied to the attached load through one of the first and second diodes and one of the third and fourth diodes.

  The controller determines the pulse on-time and off-time of the pulse width modulation control signal during each half cycle of the AC voltage, the on-time and off-time of the pulse being based on voltage detection or current detection. Control is performed to adjust the output voltage and to perform power factor correction of the AC input voltage.

  Other features and advantages of the present invention will become apparent from the following description of the invention based on the accompanying drawings.

  In the circuit of FIG. 5, the inductor is placed in the AC circuit in front of the rectifier diodes D1-D4 so that D1 and D3 have the dual function of a rectifier and boost diode. Clearly, the improved circuit has one less diode voltage drop in the power flow. Since this circuit operates at 120 Hz, switching losses are substantially eliminated, and D1-D4 and Q1-Q2 are standard speed components with the added advantage of lower conduction losses than high speed semiconductors. Q1 and Q2 are, for example, IGBTs.

  The controller detects the zero voltage crossing of the AC input signal and generates PWM drive signals for IGBTs Q1 and Q2.

  This circuit does not detect the normal line fluctuation current of +/- 10%, and in a 230 VAC circuit supplying 1 KW at a DC bus voltage of 280 VDC, with a power exceeding 0.99 with an efficiency exceeding 98% Supply rate.

  Even if the IGBT switches are driven simultaneously, they can only be made small (die size # 2) because they only conduct in alternating half cycles.

  In the circuit diagram of FIG. 6, the two cathodes of the diodes (D2, D4) are not connected to the conventional bridge rectification topology, but are connected to the main line side of the inductor. There is no difference in efficiency between the circuits of FIGS. However, in FIG. 6, each AC line is positive, and the inductors conduct only when there is no return current from the load, so they have a DC flux component.

  With this connection, the DC return bus is fixed and does not have the 120 Hz switching voltage of the previous circuit. As a result, the EMI emitted from the device is small.

  FIG. 7 shows a converter similar to the converter of FIG. 5 configured to evaluate the efficiency of a complete input converter in a bridgeless configuration. This circuit targets 1200 W of power (standard for air conditioners at 12000 btu / hour). The power IGBT switches Q1, Q2 were driven using a dedicated gate driver circuit with a 50 KHz variable duty cycle generator that provided the input signal.

The best performance was obtained using state-of-the-art silicon technology from International Rectifier. In this case, for the rectifying portion, four 8ETX06 diodes were optimized for minimum recovery time and minimum recovery current, whereas the IGBT power switch was two IRGB20B06UPD1. Table 1 below shows the input converter switching losses as a function of input line voltage and load power.

Total input conversion losses and efficiencies were measured assuming an input voltage varying from a minimum of 95V _RMS to a maximum of 265V _RMS and a constant bus voltage of 400V _DC . The test was performed at a fixed switching frequency of 50 KHz. Since the test was performed with the switch operating at a constant duty cycle over a range of input voltages for a preset bus voltage, the total loss reported here is considered worst case. In normal applications, the duty cycle (for continuous mode operation) is variable, greatly reducing the switching loss component. The following Table 2 shows the results obtained.

  The test circuit of FIG. 7 was used to compare the losses in a typical high performance bridge configuration. In an actual PFC regulator, as in the circuit of FIG. 8, it is usual to measure the IGBT collector current independently of the diode bridge current.

  The Warp2 series IGBT (International Rectifier) is the best device for this topology and makes current measurement and feedback very simple, for example, allowing current sensing to be done in series with a diode circuit, and thus Detects continuous current without switching components.

FIG. 8 shows another example of a bridgeless boost converter circuit including current sensing. The PFC function requires controlling the current drawn from the main line, shaping it and adapting it to the input voltage waveform. To achieve this, current is detected at two terminals I _sense and supplied to a control circuit (not shown) that provides a control signal DRIVE. Current sensing is achieved in this example by one or more shunt resistors R3 connected between the anode nodes of D1 and D2 and the emitter nodes of TR1 and TR2.

  Since the freewheeling diode for the IGBT is on a separate chip, unlike the intrinsic body diode in the MOSFET structure, this configuration is not an MOSFET but an IGBT switch as in US patent application Ser. No. 10/953444. Easy to use. In this example, the common line COM is defined by the anodes of the diodes D1 and D2. The output capacitor C is provided between COM and a terminal V + at the cathodes of the boost diodes D3 and D4.

  Several additional criteria have been observed to optimize bridgeless PFCs to achieve performance improvements. This goal can be addressed by the choice of an IGBT gate driver. It is important to minimize the switching loss of the IGBT for efficient operation.

Solid state gate drivers are capable of operating at switching frequencies in excess of 50 KHz, with fast rise and fall times of less than 100 nS (when loaded by two IRGB20B60) with R _s as small as 6.8 ohms. Generate. This driver function can be obtained by employing an IR4427 IC driver having the desired dynamic and current output characteristics.

  As with all power switching circuits and regulators, layout is important. Therefore, the possibility of proposing a simple plug and play solution using an integrated power module that houses the input converter topology, current sensing, and gate drivers will help electronic engineers facing the challenge of power management issues Is the correct solution for. With only two IR IPM modules, it is now possible to integrate all functions and circuits to deal with the normal driver power management functions for air conditioning applications.

  An input converter with an active PFC circuit operating at high frequencies and a bridge-free topology was analyzed and showed the benefits of power loss and efficiency.

  The benefits of these developments have been shown to be high efficiency converter operation, a reduction of over 50% of the overall motor controller size, a significant reduction in parts count, and a reduction in equipment cost and development time.

  The disclosed power factor topology, and advanced packaging, will help engineers to solve new power management challenges in temperature controlled appliances. Thus, with respect to the power factor correction standard, the technical challenge to provide an energy efficient transmission motor drive is addressed simply and cost-effectively.

  Although the invention has been described with reference to specific embodiments thereof, it will be apparent to those skilled in the art that there are many other variations and modifications and other uses. Accordingly, the present invention is not limited by the specific disclosure herein.

1 is a schematic diagram showing the configuration and operation of a conventional inverter front end. Fig. 9 is a schematic diagram illustrating the basic bridgeless converter topology disclosed in 10/953444 and its operation during the positive half cycle. 3 is a schematic diagram illustrating the converter of FIG. 2 and its operation during a negative half cycle. 1 is a schematic diagram of a conventional boost converter with PFC. 1 is a schematic diagram of a bridgeless PFC circuit according to a first embodiment of the present invention; 4 is a schematic diagram of a bridge-free PFC circuit according to a second embodiment of the present invention; 1 is a schematic diagram of a PFC circuit without a bridge according to a modification of the first embodiment. 6 is a schematic diagram of a bridge-free PFC circuit according to a third embodiment of the present invention;

Explanation of symbols

C capacitor COM common line D diode D1 diode D2 diode D3 diode D4 diode DB boost diode DRIVE control signal IL current L inductor M shunt switch M1 MOSFET
M2 MOSFET
Q1 transistor Q2 transistor R resistor R3 shunt resistor TR1 transistor TR2 transistor V + terminal

Claims (17)

A first end connected to the first AC input terminal; and a second end connected to the first connection located between the anode of the first diode and the first terminal of the first switch. Boost inductor,
A second terminal of the first switch connected to a common line;
A parallel circuit of a capacitor and a load terminal connected between the cathode of the first diode and the common line;
A series circuit of a second diode and a second switch connected between the cathode of the first diode and the common line;
A second AC input terminal connected to a second connection located between the anode of the second diode and the second switch;
Another boost inductor connected between the second AC input terminal and the second connection;
A control input connected to control the first and second switches to perform power factor correction on the power applied to the load terminal;
A bridgeless PFC boost converter comprising third and fourth diodes having an anode connected to the common line and a cathode connected to the first and second AC input terminals, respectively.   The bridgeless PFC boost converter of claim 1, further comprising a resistor network interconnecting the control input, the first and second switches, and the common line.   Each of the first and second switches has a pair of main terminals connected to a common line and corresponding connections of the first and second connections, respectively, and a gate terminal connected to the control input The PFC boost converter without a bridge according to claim 1.   4. The bridgeless PFC boost converter of claim 3, further comprising a resistor network interconnecting the control input, the gate terminal, and the common line.   The bridgeless PFC boost converter of claim 1, further comprising a control circuit coupled to a control input that controls the first and second switches in response to currents of the first and second switches.   The control circuit of claim 1, further comprising a control circuit connected to a control input that controls the first and second switches in response to a voltage at the first and second AC input terminals and an output voltage between the load terminals. PFC boost converter without bridge.   The bridgeless PFC boost converter of claim 6, wherein the control circuit is adapted to detect a zero voltage crossing at the AC input terminal.   The bridgeless PFC boost converter according to claim 1, wherein the first and second switches are IGBTs. A first end connected to the first AC input terminal; a second end connected to the first connection located between the anode of the first diode and the first terminal of the first switch; A boost inductor having:
A parallel circuit of a capacitor and a load terminal connected between the cathode of the first diode and a common line;
A series circuit of a second diode and a second switch connected to the cathode of the first diode;
A second AC input terminal connected to a second connection defined between the anode of the second diode and the first terminal of the second switch;
Another boost inductor connected between the second AC input terminal and the second connection;
A control input connected to control the first and second switches to perform power factor correction on the power applied to the load terminal;
And a second terminal of each of the first and second switches is a PFC boost converter without a bridge connected to a current detection line connected to the common line by a shunt resistor.   10. A bridgeless device according to claim 9, further comprising third and fourth diodes respectively connected in parallel with the first and second switches, the cathodes of which are connected to corresponding first and second connections. PFC boost converter.   The bridgeless PFC boost converter of claim 10, wherein the anodes of the third and fourth diodes are connected to a common line.   The bridgeless PFC boost converter of claim 9, further comprising a control circuit coupled to a control input for controlling the first and second switches in response to currents of the first and second switches.   The control circuit according to claim 9, further comprising a control circuit connected to a control input for controlling the first and second switches in response to a voltage at the first and second AC input terminals and an output voltage between the load terminals. PFC boost converter without bridge.   14. The bridgeless PFC boost converter of claim 13, wherein the control circuit is adapted to detect a zero voltage that intersects at the AC input terminal.   The bridgeless PFC boost converter according to claim 9, wherein the first and second switches are IGBTs.   The bridgeless PFC boost converter according to claim 9, wherein the anodes of the third and fourth diodes are connected to a common line.   10. The bridgeless PFC boost converter of claim 9, further comprising a control circuit connected to a control input that controls the first and second switches in response to voltages on the detection line and the common line.

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