WO2010142190A1

WO2010142190A1 - Large power electromagnetic cooker circuit based on system-on-chip (soc)

Info

Publication number: WO2010142190A1
Application number: PCT/CN2010/072819
Authority: WO
Inventors: 丘守庆; 许申生; 吕真; 李鹏
Original assignee: 深圳市鑫汇科科技有限公司
Priority date: 2009-06-08
Filing date: 2010-05-15
Publication date: 2010-12-16
Also published as: CN101909375B; CN101909375A

Abstract

A large power electromagnetic cooker circuit based on system-on-chip (SoC) is provided, including a bridge rectifier (1), a filter (2), a power inverter circuit and a control unit (6). The control unit (6) is based on SoC that is integrated with CPU, a plurality of comparators, a second AC-DC converter, a voltage dividing circuit, an integral circuit, an inverter, a zero cross detecting circuit and a communication interface. The power inverter circuit is a half-bridge resonance circuit (3), which is driven by an outer driving circuit (7) to which complemented pulse signal and switch signal outputted by CPU in SoC. The large power electromagnetic cooker circuit based on SoC also includes a self-protective resonance tracking circuit, a pot detecting circuit, a surge detecting circuit and a multi-points temperature detecting circuit (9). The large power electromagnetic cooker circuit based on SoC has advantages of low manufacturing cost, small maintenance complexity, high reliability, and high parching detection sensitivity. A pot body and the cooker can be separated from each other. The cooker with a small volume is applicable to different types of pots, and is convenient to users.

Description

High-power induction cooker circuit based on SoC chip

Technical field

The invention belongs to the technical field of induction cooker heated by electric energy, in particular to a system based on SoC (System on a Chip) High-power induction cooker circuit for chips.

Background technique

The high-power induction cooker is a kitchen heating device used to heat and cook food. It uses a high-frequency alternating current to generate an alternating magnetic field through a coil. The alternating magnetic field generates an induced current at the bottom of the iron pot. Eddy currents and eddy currents cause the pot body to heat up at a high speed. The induction cooker has no open flame, no smoke, no exhaust gas, and has a series of advantages such as fast heating speed, high thermal efficiency, uniform heating, clean and hygienic, energy saving and environmental protection, and good safety. There is a broad market space in the fields of train dining car, ship restaurant, subway fast food, hotel, hotel, Chinese and Western fast food industry, military, enterprise, institutional canteen, hot pot restaurant and bagged fried food.

Domestic high-power induction cookers have the following technical defects:

1, using more complex hardware circuits (such as CD4046 and PWM modulation IC The circuit formed together) performs frequency tracking on the resonant circuit so that the driving frequency of the IGBT is always higher than the resonant frequency, so that the IGBT Stable and reliable work in the inductive zone, the disadvantage of this is that the hardware circuit is complex, the system reliability is low, and the cost is high.

2 The reliability of power control, anti-jamming and protection technologies under high current operation is insufficient. To this end, people have designed the pot body and furnace fixed mode, which avoids the protection of the pot, the pot, the pot, etc., does not need to check the pot, the control is simple, but the equipment is bulky, which limits the application.

3, ubiquitous The number of components is large, the number of fault points is large, the production and maintenance are difficult, and the overall cost is high.

Summary of the invention

In order to avoid the above defects existing in the existing high-power induction cooker technology, the present invention provides a SoC chip-based high-power induction cooker circuit, the SoC thereof Integrated CPU, several comparators, AC-DC Converters, voltage divider circuits, integration circuits, inverters, zero-crossing detection circuits, and communication interfaces, and a variety of optimized design protection circuits are designed to improve the operational reliability of high-power induction cookers and reduce production costs.

The invention is based on SoC The high-power induction cooker circuit of the chip comprises a rectifier bridge, a filter, a power inverter circuit and a control unit, and is characterized in that:

The control unit uses a SoC chip (System on a Chip, system-on-chip or system-on-chip) The chip integrates a CPU, first to fourth comparators, a second AC-DC converter, a voltage dividing circuit, an integrating circuit, an inverter, a zero-crossing detecting circuit, and a communication interface;

The power inverter circuit is a half bridge resonant circuit, and the CPU in the SoC chip Outputting a complementary pulse signal and a switching signal to an external driving circuit to drive the half bridge resonant circuit to operate;

Further includes:

Self-protecting resonant tracking circuit, the circuit including the CPU and the second AC-DC in the SoC chip a converter, a voltage dividing circuit, a second comparator, a third comparator, and an off-chip resonant current sampling circuit, the sampled resonant current is passed through the second AC-DC After the converter is rectified, two signals are generated by the voltage dividing circuit, and the two inputs of the CPU are input through the second comparator and the third comparator, respectively. Adjusting the frequency of the output complementary pulse signal according to the two signals from the second and third comparators to make the IGBT in the half bridge resonant circuit The switching frequency is always slightly higher than the resonant frequency, or the output of the complementary pulse signal is turned off to achieve the protection function;

a pot circuit comprising a CPU, a first comparator and an off-chip resonant current sampling circuit in the SoC chip;

a surge detection circuit including the SoC Integral, fourth comparator, inverter, and off-chip input current sampling circuit and first AC-DC converter, first AC-DC a converter is coupled to the input current sampling circuit, an input of the integrator is coupled to a negative output of the first AC-DC converter, an output of the integrator is coupled to the fourth comparator, and a fourth comparator output is Inverter connected The CPU within the SoC chip;

Multi-point temperature detection circuit.

The high-power induction cooker circuit of the invention adopts SoC chip technology, and the SoC chip has a built-in CPU The core control technology has high chip integration and simple peripheral application circuit, which greatly reduces the difficulty and cost of production and maintenance.

It has a protection circuit such as a resonance tracking circuit, a detection pot circuit, and a surge detection circuit. These circuits are integrated in the SoC except for current sampling. In the chip, and the surge detection and power detection share a current sampling circuit, the resonance tracking and the detection pot share a current sampling circuit, which reduces the scattered wiring interference and greatly improves the reliability.

It uses a multi-point temperature measuring circuit to detect the temperature of multiple points on the furnace surface. It avoids the fact that the existing induction cooker only detects the central temperature, which can not timely and accurately judge the dry burning defects, and improves the sensitivity of the induction cooker dry burning detection.

Since the invention adopts a special resonance tracking circuit, a detection pot circuit, a surge detection circuit and the like to make a high-power induction cooker The design is free from the constraints of the traditional pot body and furnace fixed design mode. The pot body and the furnace can be separated, the volume is reduced, and different pots can be used to provide convenience for the user.

DRAWINGS

Figure 1 is a schematic block diagram of the present invention;

Figure 2 is a circuit diagram of an embodiment thereof;

3 is an internal circuit diagram of a CHK-BQ002V1.0 type SoC chip used in the embodiment of FIG. 2;

Figure 4 shows the waveform of the complementary pulse signal output from the SoC chip.

detailed description

The invention is further illustrated below.

Referring to Figure 1-3, the high-power induction cooker circuit includes: a rectifier bridge 1, a filter 2, a power inverter circuit 3, and a control unit 6 , temperature detection circuit 9, control switch and display 10, self-protection resonant tracking circuit, detection pot circuit, surge detection circuit, etc.

The control unit 6 adopts the CHK-BQ002V1.0 SoC chip designed by the applicant, and the CPU is integrated in the chip ( Central processing unit), first to fourth comparators CP1-CP4, second AC-DC converter, voltage dividing circuit F1, integrating circuit J1 , inverter, zero-crossing detection circuit and communication interface.

The power inverter circuit 3 uses a half bridge resonant circuit, and the CPU in the SoC chip outputs complementary pulse signals and switching signals to The external drive circuit 7 pushes the half-bridge resonant circuit 3 to work. Referring to FIG. 2, the half bridge resonant circuit 3 includes a power tube IGBT1, a power tube IGBT2, an electromagnetic coil L0, and a capacitor. C4, C7, C12, C13, the collector of the power tube IGBT1 is connected to the positive output terminal of the rectifier bridge BG1 (the rectifier bridge BG1 is the rectifier bridge 1), and the emitter is connected. The collector of IGBT2 and one end of electromagnetic coil L0, the emitter of IGBT2 is connected to the negative output of rectifier bridge BG1, and the capacitor C7 is connected in parallel with power tube IGBT1. Between the emitter and the collector, the capacitor C13 is connected between the emitter and the collector of the power tube IGBT2, and the capacitors C4 and C12 are connected in series and connected to the rectifier bridge BG1. The other end of the electromagnetic coil L0 is commonly connected between the two outputs. In a specific embodiment, the driving circuit 7 for driving the half-bridge resonant circuit outside the SoC chip adopts IR2113. Chip (see U2 in Figure 2).

The self-protected resonant tracking circuit includes a CPU, a second AC-DC converter, and a voltage dividing circuit F1 in the SoC chip The second comparator CP2, the third comparator CP3 and the off-chip resonant current sampling circuit 8 , the sampled resonant current is rectified by the second AC-DC converter, and passed through the voltage dividing circuit F1 Two signals are generated to be input to the two inputs of the CPU through the second comparator CP2 and the third comparator CP3, and the CPU is based on the second comparator CP2 and the third comparator CP3. The two signals adjust the frequency of the output complementary pulse signal to make IGBT1 and IGBT2 in the half-bridge resonant circuit The switching frequency is always slightly higher than the resonant frequency, or the output of the complementary pulse signal is turned off to achieve protection. In a specific embodiment, the resonant current sampling circuit 8 samples the current in the resonant tank through the current transformer T3 (see Figure 2). ).

The detecting pot circuit includes a CPU in the SoC chip, a first comparator CP1, and an off-chip resonant current sampling circuit 8. The sampled resonant current is input to the first comparator CP1 and compared with the reference voltage V _ref1 , and the CPU determines whether the furnace surface has a pot according to the number of pulses output by the first comparator CP1 during the pot counting period. If the number of pulses is less than the set threshold, it is determined that there is a pot on the furnace surface, and vice versa, it is determined that there is no pot on the furnace surface.

The surge detecting circuit includes an integrator J1, a fourth comparator CP4, an inverter, and an off-chip input current sampling circuit 4 and a first AC-DC converter 5 in the SoC chip, the first AC - DC converter 5 is connected to the input current sampling circuit 4, the input end of the integrator J1 is connected to the negative output terminal of the first AC-DC converter 5 outside the chip, and the output terminal is connected to the fourth comparator CP4, The four comparator CP4 outputs are connected to the CPU within the SoC chip through the inverter. When a surge voltage occurs in the 220V 50Hz AC power supply loop, the first AC-DC converter 5 inputs a negative pulse voltage to the integrator J1 in the SoC chip, and the negative pulse voltage is integrated and input to the fourth comparator CP4 and The reference voltage V _{ref3 is} compared to determine whether the surge exceeds the set value. If it exceeds, it will be input to the positive pulse of the CPU in the SoC chip through the inverter, so that the CPU can perform corresponding processing to protect the safe operation of the system. In a specific embodiment, the input current sampling circuit 4 samples the current in the power supply AC input loop through the current transformer T2 (see Figure 2).

a positive output terminal of the first AC-DC converter 5 outside the SoC chip is connected to a CPU in the SoC chip One input, input the sampling current into the CPU Used to determine the current power of the induction cooker. It can be seen that the current surge, the voltage surge and the detection of the whole machine power current are used in the present invention to share the same current sampling circuit (ie, the input current sampling circuit 4 ) technical solution. The AC component is extracted as a reference for surge protection, and the DC component is used as a reference for the operating current of the whole machine.

The multi-point temperature detecting circuit 9 includes a first furnace surface temperature sampling circuit, a second furnace surface temperature sampling circuit, and an IGBT The temperature sampling circuit, the temperature sensor of the first furnace surface temperature sampling circuit is installed at the center of the heating coil disk, and the temperature sensor of the second furnace surface temperature sampling circuit is installed between the center of the disk of the heating coil disk and the edge of the disk and at a distance The distance from the center of the disk is the radius of the heating coil 1/3-2/3, IGBT temperature sampling circuit is used to detect the temperature of two power transistors IGBT1 and IGBT2. The temperature signals collected by the three temperature sampling circuits pass through different interfaces ( The SoC chip is input to the 5th, 11th, and 13th pins of the CHK-BQ002V1.0 SoC chip.

Wherein, the second furnace surface temperature sampling circuit comprises at least two temperature sensors uniformly distributed on the heating coil disk to heat the center of the coil disk as a center, R/3-2R/3 is the radius of the circumference, where R is the radius of the heating coil disk. The output of multiple temperature sensors of the second furnace surface temperature sampling circuit is connected to the CHK-BQ002V1.0 type SoC The 13 feet of the chip.

Referring to FIG. 4, the complementary pulse signals output by the CPU in the SoC chip are complementary two sets of PFM (pulse Frequency modulation ) The pulse signal has a duty cycle of less than 0.5. They push the half-bridge resonant circuit 3 through the external drive circuit 7. PFM The larger the period T of the pulse signal, the larger the output power of the induction cooker.

The communication interface in the SoC chip is a serial interface, and the interface implements an on-chip CPU of the SoC chip. Communication with external control switches and displays.

The zero-crossing detection circuit in the SoC chip detects the 220V50Hz AC signal and outputs it to the CPU. Process accordingly to protect the safe operation of the system. Switching on and off when the AC crosses zero can reduce the switching noise of the induction cooker, reduce the impact on the IGBT, and prolong the service life of the IGBT.

The pin functions of the CHK-BQ002V1.0 SoC chip are:

15 , 16 power pins,

7 , 9 , 10 grounding feet,

1 , 3 , 8 , 19 empty feet,

2, 4, 6 complementary pulse signal and switch signal output port,

5 IGBT temperature sampling input port,

11 , 13 The first and second furnace surface temperature sampling input ports,

17 zero-crossing detection input,

21 speaker control output,

23, 25 encoder input,

26 , 27 , 28 panel communication interface,

24 fan control port,

22 mains voltage detection port,

18 , 20 resonant current sampling input port,

12 , 14 Input current sampling input.

This high-power induction cooker circuit uses SoC chip technology, SoC There is only a basic circuit for half-bridge induction heating outside the chip. The basic circuit provides working status to the SoC chip through two current transformers T2 and T3. SoC The chip detects the power supply and temperature, and realizes an induction heating system with constant power, pot detection, overcurrent, overvoltage, surge and the like. The SoC chip is based on the power value emitted by the human machine interface, 2, 4 by the SoC chip. The foot output complementary pulse signal causes the half bridge resonant circuit 3 to operate at the set power; the output frequency is adjusted according to the current value fed back by the low frequency current transformer T2 to make the power constant; according to the high frequency current transformer T3 The feedback current value adjusts the frequency of the complementary pulse signal output by the 2nd and 4th pins of the SoC chip, performs state protection, and adjusts to make IGBT1 and IGBT2 The drive frequency is always slightly higher than the resonant frequency, so IGBT1 and IGBT2 Can work stably and reliably in the emotional zone. The use of bad cookware, the system automatically adjusts to the appropriate power range according to the state of the protection circuit to ensure reliable operation.

Claims

1, one based on SoC The high-power induction cooker circuit of the chip comprises a rectifier bridge, a filter, a power inverter circuit and a control unit, and is characterized in that:

The control unit adopts a SoC chip, and the chip integrates a CPU, first to fourth comparators, and a second AC-DC. Converter, voltage dividing circuit, integrating circuit, inverter, zero-crossing detecting circuit and communication interface;

The power inverter circuit is a half bridge resonant circuit, and the CPU in the SoC chip Outputting a complementary pulse signal and a switching signal to an external driving circuit to drive the half bridge resonant circuit to operate;

Further includes:

Self-protecting resonant tracking circuit, the circuit including the CPU and the second AC-DC in the SoC chip a converter, a voltage dividing circuit, a second comparator, a third comparator, and an off-chip resonant current sampling circuit, the sampled resonant current is passed through the second AC-DC After the converter is rectified, two signals are generated by the voltage dividing circuit and input to the two input ends of the CPU through the second comparator and the third comparator respectively;

a pot circuit comprising a CPU, a first comparator and an off-chip resonant current sampling circuit in the SoC chip;

a surge detection circuit including an integrator, a fourth comparator, an inverter, and an off-chip input current sampling circuit and a first AC-DC in the SoC chip a converter, a first AC-DC converter coupled to the input current sampling circuit, the input of the integrator and the first AC-DC a negative output of the converter is connected, an output is connected to the fourth comparator, and a fourth comparator output is connected to the CPU in the SoC chip through the inverter;

Multi-point temperature detection circuit.

2. The SoC based on claim 1 The high-power induction cooker circuit of the chip is characterized in that: the multi-point temperature detecting circuit comprises a first furnace surface temperature sampling circuit, a second furnace surface temperature sampling circuit and an IGBT The temperature sampling circuit, the temperature sensor of the first furnace surface temperature sampling circuit is installed at the center of the heating coil disk, and the temperature sensor of the second furnace surface temperature sampling circuit is installed between the center of the disk of the heating coil disk and the edge of the disk and at a distance The distance from the center of the disk is the radius of the heating coil 1/3-2/3.

3. The SoC based on claim 2 The high-power induction cooker circuit of the chip is characterized in that: the second furnace surface temperature sampling circuit comprises at least two temperature sensors uniformly distributed on the heating coil disk to heat the center of the coil disk as a center, R/3-2R/ 3 On the circumference of the radius, where R is the radius of the heating coil disk.

4. The SoC chip-based high power induction cooker circuit according to claim 1, wherein: the first AC-DC outside the SoC chip The positive output of the converter is connected to an input of the CPU in the SoC chip, and the sampling current is input to the CPU for determining the current power of the induction cooker.

5. The SoC chip-based high power induction cooker circuit according to claim 1, wherein: the CPU in the SoC chip The complementary pulse signals output are complementary two sets of PFM pulse signals, and the duty ratio of the pulse signals is less than 0.5.

6. The SoC chip-based high power induction cooker circuit according to claim 1, wherein the half bridge resonant circuit comprises a power tube IGBT1 , power tube IGBT2, electromagnetic coil L0 and capacitor C4, C7, C12, C13, power tube IGBT1 collector connected to the positive output of the rectifier bridge, the emitter is connected to IGBT2 One end of the collector and the electromagnetic coil L0, the emitter of the IGBT2 is connected to the negative output of the rectifier bridge, and the capacitor C7 is connected between the emitter and the collector of the power tube IGBT1, and the capacitor C13 Connected between the emitter and the collector of the power tube IGBT2, the capacitors C4 and C12 are connected in series and connected between the two output ends of the rectifier bridge and connected to the electromagnetic coil L0 The other end.

7. The SoC chip-based high power induction cooker circuit according to claim 1, wherein: said SoC The communication interface in the chip is a serial interface, which realizes the communication between the CPU of the SoC chip and the external control switch and display.

8. The SoC chip-based high power induction cooker circuit according to claim 1, wherein said resonant current sampling circuit passes current transformer T3 The current in the resonant tank is sampled, and the input current sampling circuit samples the current in the AC input circuit through the current transformer T2.

9. The SoC chip-based high power induction cooker circuit according to claim 1, wherein said SoC The chip has the following function pins: complementary pulse signal and switch signal output port, speaker control output port, fan control output port, IGBT Temperature sampling input port, first and second furnace surface temperature sampling input port, zero-crossing detection input port, mains voltage detection port, resonant current sampling input port, input current sampling input port, and panel communication interface.