BÁO CÁO NGHIÊN CỨU VỀ BỘ CHUYỂN ĐỔI MA TRẬN TẦN SỐ CAO (High Frequency Matrix Converter)

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Electrical Machines & Drives Research Group
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High Frequency Matrix Converter
High Frequency Matrix Converter
Nam Nguyen-Quang
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The University of Sheffield
Electrical Machines & Drives Research Group
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• Background information
• Proposed converter
• Results to-date
• Conclusion
OVERVIEW
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• Induction Heating (IH)
Î Basic Principles
Î Resonant Tanks
• Conventional Converters for IH
Î Current Source Inverter (CSI)
Î Voltage Source Inverter (VSI)
BACKGROUND INFORMATION
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• A coil (work-head) creates a magnetic field, which

induces a current in a conductor (work-piece)
• Large current is required Ö the use of resonant
tanks
• Loose coupling between
the work-head and the
work-piece
Ö high
quality factor
INDUCTION HEATING – BASIC PRINCIPLES
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• Skin depth: the depth from surface, at which the
current density is about 1/3 of its surface value.
• Skin depth decreases when frequency increases.
• Frequency bands have been defined for IH:
Î Supply-frequency: 50 – 540 Hz
Î Medium frequency: 500 Hz – 50 kHz
Î Radio frequency: 50 kHz – 10 MHz
Î Microwave: 10 MHz upwards
INDUCTION HEATING – BASIC PRINCIPLES
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INDUCTION HEATING – RESONANT TANKS
Series resonant tank
• High impedance at
high frequency

• Used with VSIs
Parallel resonant tank
• Low impedance at high
frequency
• Used with CSIs

C L
R

C
L
R
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• Higher order resonant tanks have been used
• Most widely reported and useful is the LLC tank
INDUCTION HEATING – RESONANT TANKS
C
L
2

R
L
1

Î High impedance at
high frequency, can
be used with VSIs

Î Large current can
circulate through C
and L
2
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• First widely used topology
• Run at the resonant frequency
• Power is only controlled by amplitude modulation

CONVENTIONAL CONVERTERS – CSI
C
L
RI

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• Two utility supply interfaces
CONVENTIONAL CONVERTERS – CSI
Low Power High Power
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• Advantages
Î Low reactive power flow

Î Constant operating frequency
• Disadvantages
Î Effect of stray inductance: limit on frequency,
and physical cable length
Î High switching losses
Î Non-unity power factor, high harmonic
distortion
CONVENTIONAL CONVERTERS – CSI
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• More emergent technology
• Power can be controlled by frequency, amplitude,
or phase angle (phase-shift) modulation

CONVENTIONAL CONVERTERS – VSI
C L
RV

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0 1 2 3 4 5 6 7 8 9 10
S1
S2
S3
S4

Gate signals

0 1 2 3 4 5 6 7 8 9 10
-30
-20
-10
0
10
20
30
Time (
μ
s)
Output voltage and current
12
• Frequency modulation
Î The simplest and most straightforward method
Î An inductive load is needed for ZVS Ö an
above resonance operating condition
CONVENTIONAL CONVERTERS – VSI
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• Amplitude modulation
Î Varying the DC link voltage
Î Operating just above the resonant frequency

CONVENTIONAL CONVERTERS – VSI
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• Phase angle (phase-shift) modulation: Many
variants, with or without lossless snubbers
CONVENTIONAL CONVERTERS – VSI
0 1 2 3 4 5 6 7 8 9 10
S1
S2
S3
S4

Gate signals
0 1 2 3 4 5 6 7 8 9 10
-30
-20
-10
0
10
20
30
Time (
μ
s)
Output voltage and current
Current
Voltage
0 1 2 3 4 5 6 7 8 9 10
S1
S2
S3
S4

Gate signals
0 1 2 3 4 5 6 7 8 9 10
-30
-20
-10
0
10
20
30
Time (
μ
s)
Output voltage and current
Current
Voltage
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0 1 2 3 4 5 6 7 8 9 10
S1
S2
S3
S4

Gate signals
0 1 2 3 4 5 6 7 8 9 10
-30
-20
-10

0
10
20
30
Time (
μ
s)
Output voltage and current
Current
Voltage
15
• Using lossless snubbers, ZVS in both legs
CONVENTIONAL CONVERTERS – VSI
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• Advantages
Î Many power control methods, some with ZVS
or ZCS, stray capacitances can be utilised
Î Stray inductances can be utilised
• Disadvantages
Î Large current harmonics at line side, non-unity
power factor
Î Bulky and unreliable DC link capacitor
CONVENTIONAL CONVERTERS – VSI
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• Basis for single phase high frequency matrix
converter
CONVENTIONAL CONVERTERS – VSI
Rectifier LLC Resonant TankH-Bridge
Inverter
Line
Filter
C
L
2

R
L
1

V
Source

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• Single-phase to single-phase matrix converter
(Single phase MC)
Î Topology
Î Problems
• Three-phase to single-phase matrix converter
(Three phase MC)
Î Topology
Î Problems

PROPOSED CONVERTER
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• Topology

SINGLE PHASE MC – TOPOLOGY
V
A

V
B


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• The converter is expected to possess
Î Unity power factor, sinusoidal input current
Î ZVS and ZCS in one row, ZVS in other row
Î PWM power control over a wide range
SINGLE PHASE MC – TOPOLOGY
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• Commutation problem: Modified voltage
commutation

• Utility supply interface: Small line filter
• Power control: PWM with soft switching
SINGLE PHASE MC – PROBLEMS
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• Topology
THREE PHASE MC – TOPOLOGY
V
A

V
B

V
C

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• Commutation problem: directly applying
switching pattern of single-phase version may
create large distortion in input currents
• Utility supply inferface: small line filter
• Power control: PWM control with soft switching is
preferrable
THREE PHASE MC – PROBLEMS
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• Literature survey
• Reference system
• Simulations of single phase MC
RESULTS TO-DATE
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• Principles of induction heating
• Resonant converters for induction heating
• Analysis methods for resonant-mode inverters
• Utility interfaces for converters
• Other converters
RESULTS – LITERATURE SURVEY
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